Los Angeles Chargers QB Trey Lance Thread

Originally posted by YACBros85:
QBR isn't a perfect stat? No one even knows the formula used to come up with those numbers but for some reason they get thrown around as if they mean something. I know exactly how the stats I use are formulated and anyone with a half a brain understands them as well. No one should bring up film to defend their claims without actually providing the film to defend their claims. Simple as that.

None of the stats are perfect. That's the point. You're claiming to be a stat guy but you're mainly citing a few select stats that are just as much team stats as they are individual stats while ignoring (or at least never citing) another stat (Among many others) that is designed to account for individual performance only.

Anybody can cherry pick stats and misapply what they actually show and make arguments. When that happens you get discrepancies like we have with the Texans game as an example. Trey had an awesome passer rating in that game. Would be tops in the league over the course of the season. He had a bad QBR. Would be near the bottom of the league over the course of the season. A real stat guy is going to look at them all and use them in context to get a better idea of what actually happened.

Originally posted by SmokeyJoe:

Originally posted by YACBros85:
QBR isn't a perfect stat? No one even knows the formula used to come up with those numbers but for some reason they get thrown around as if they mean something. I know exactly how the stats I use are formulated and anyone with a half a brain understands them as well. No one should bring up film to defend their claims without actually providing the film to defend their claims. Simple as that.

None of the stats are perfect. That's the point. You're claiming to be a stat guy but you're mainly citing a few select stats that are just as much team stats as they are individual stats while ignoring (or at least never citing) another stat (Among many others) that is designed to account for individual performance only.

Anybody can cherry pick stats and misapply what they actually show and make arguments. When that happens you get discrepancies like we have with the Texans game as an example. Trey had an awesome passer rating in that game. Would be tops in the league over the course of the season. He had a bad QBR. Would be near the bottom of the league over the course of the season. A real stat guy is going to look at them all and use them in context to get a better idea of what actually happened.

You are using a stat that is a big unknown. If you can give me the formula they use to determine that number I would be more inclined to accept it. But you can't. Using a stat that you don't even understand yourself means that the only reason why you like it is because it fits your agenda. I can tell you how every single stat I use is formulated and why I like them for evaluating player performance.

The same argument you are using to combat the stats I used could be used for why than we cannot evaluate any other player on the field. WR stats would than be useless because you cannot account for scheme, QB or pass pro. Same thing for RB's and the entire defense who relies on the other 10 guys around them to do their job.

Originally posted by YACBros85:
You are using a stat that is a big unknown. If you can give me the formula they use to determine that number I would be more inclined to accept it. But you can't. Using a stat that you don't even understand yourself means that the only reason why you like it is because it fits your agenda. I can tell you how every single stat I use is formulated and why I like them for evaluating player performance.

The same argument you are using to combat the stats I used could be used for why than we cannot evaluate any other player on the field. WR stats would than be useless because you cannot account for scheme, QB or pass pro. Same thing for RB's and the entire defense who relies on the other 10 guys around them to do their job.

Yes! Basic stats that people would typically cite for a WR, like yardage, yardage per reception, tds, etc, are going to depend on factors unrelated to their individual performance. And no, I'm not selecting stats, ignoring others, and making an argument at all. That's what you're doing. You're claiming to be a stat guy, but cherry picking certain stats and ignoring others.

Forget about QBR, which was just an example of stat that can be used. How about PFF grades? You've cited stats from PFF in the past. In the Texans game Trey Lance's overall grade was lower than his grade in his start against Arizona. He was in the high 50s I believe (not sure because I couldn't care less about PFF stats personally).

Passer rating, YPA, completion percentage, td percentage, don't give a full or even a necessarily accurate idea of individual performance. A play where a qb throws a bubble screen that goes for a 70 yard td is going to be viewed the same as a play where a qb breaks a tackle in the backfield, extends the play for 3-4 seconds and breaks the defense down, and hits a 50 yard pass downfield to a receiver who takes it another 20 yards into the endzone.

Originally posted by SmokeyJoe:

Originally posted by YACBros85:
You are using a stat that is a big unknown. If you can give me the formula they use to determine that number I would be more inclined to accept it. But you can't. Using a stat that you don't even understand yourself means that the only reason why you like it is because it fits your agenda. I can tell you how every single stat I use is formulated and why I like them for evaluating player performance.

The same argument you are using to combat the stats I used could be used for why than we cannot evaluate any other player on the field. WR stats would than be useless because you cannot account for scheme, QB or pass pro. Same thing for RB's and the entire defense who relies on the other 10 guys around them to do their job.

Yes! Basic stats that people would typically cite for a WR, like yardage, yardage per reception, tds, etc, are going to depend on factors unrelated to their individual performance. And no, I'm not selecting stats, ignoring others, and making an argument at all. That's what you're doing. You're claiming to be a stat guy, but cherry picking certain stats and ignoring others.

Forget about QBR, which was just an example of stat that can be used. How about PFF grades? You've cited stats from PFF in the past. In the Texans game Trey Lance's overall grade was lower than his grade in his start against Arizona. He was in the high 50s I believe (not sure because I couldn't care less about PFF stats personally).

Passer rating, YPA, completion percentage, td percentage, don't give a full or even a necessarily accurate idea of individual performance. A play where a qb throws a bubble screen that goes for a 70 yard td is going to be viewed the same as a play where a qb breaks a tackle in the backfield, extends the play for 3-4 seconds and breaks the defense down, and hits a 50 yard pass downfield to a receiver who takes it another 20 yards into the endzone.

I provided context to those stats. Out of those 105 yards in the first half, 16 of them came from YAC. Even if you take away the 45 yarder to Deebo, his efficiency stats in that game were still spectacular. So perhaps you missed that part of my post because you were so anxious to debunk my argument.

Data analysis is becoming more and more prevelant in today's NFL. Get used to it or atleast provide something we can all understand to back up your claims. I am all for watching film analysis but those who like to use film as proof never seem to provide any. Perhaps its because they aren't as fluent in film as they claim to be. Which is probably because they actually haven't a clue what they are even watching in the first place.

How is Total Quarterback Rating Computed?Total Quarterback Rating is built on two ideas: measuring the expected points added by a quarterback and translating these expected points added to winning probabilities. Let's go through each of these components separately.

Expected Points AddedFirst, let's try to understand expected points added. Really, football and any other game is simple: score more points than your opponent. Then, if one could measure 'how many points' a particular player contributes to your team's total, then you could figure out definitively how much a player helps you win.

Each down and distance from each spot on the field in the NFL has an expected points scored on the drive. For example, if it is first and 1 from the opponents' 1 yard line, the expected points on the drive is almost certainly around 7. If it is 4th and 10 from your own 1 yard line, the expected points should be nearly 0. Computing the change in expected points from one play to the next lets us determine the 'value' of a play. Let's do an example.

It is 3rd and 10 at our own one yard line, the expected points on this drive are nearly 0. However, the running back rips off a 98 yard run to the opponents 1 yard line. Now the expected points on the drive is about 7. The previous play added 7 expected points to my team's total. If we determined that the running back was solely responsible for the outcome of that play, then the running back contributed 7 expected points to his team's total from that one play. We can compute a player's expected points added over all plays in the game this way to figure out how much a player contributes to their team's success. This is a lot like RE24 in baseball.

The first step in determining total QBR is determining the quarterback's expected points added over the course of the game. Because there are 11 players on each side of the ball, it can be hard to assign credit for the outcome of a play. In fact, entire articles have been written trying to assign credit for specific outcomes to one player or another.

However, for quarterbacks, the problem is often a lot simpler. For example, the quarterback gets credited for completing the pass and a few yards after contact, the rest is the receiver. A similar judgement and division of credit can be made for quarterback runs and sacks though that information is still proprietary to ESPN. In this way, we can calculate the expected points added by a quarterback. Now we need to convert this to a meaningful scale.

Logistic Regression for Winning ProbabilityAfter computing a quarterback's expected points added, we want to convert this number to something easy-to-digest. In particular, converting from expected points added to estimated winning probability is about as valuable as a conversion one could make. Why? Because then the numbers are easy to interpret.

A 50% chance at winning is a perfectly average performance; you'll win half the time you'll lose half the time. A QBR of 75 is significantly better. A QB with a season-long QBR of 75 should be expected to win 75% of their games if they play against league-average opponents. All else held equal, a quarterback with a 75 rating should lead your team to a 12-4 record. Most importantly, a perfect QBR of 100 is actually impossible to attain – as it should be! No matter how well your quarterback performs, you cannot ever guarantee a win because the other quarterback could always do the exact same thing.

How is the conversion from expected points to winning probability done? This is the perfect opportunity to use logistic regression. Logistic regression transforms 'continuous' predictive variables (like expected points added) into probabilities of an event happening. In particular, the logistic regression model fits a curve (the logistic curve) to existing data to translate from expected points added to winning probability. It is kind of like a least squares regression line or line of best fit in this way.

(As an aside, a good tool to learning logistic regression is this "hands on, practical" book that I've used before. Logistic regression is one of the top most important tools that data scientists and statisticians should learn. I consider it a "must know".)

While not entirely correct, if the data is sufficiently nicely distributed, one could actually think of total quarterback rating as a percentile of expected points added over all time. Then, a 99.9 QBR would correspond to the 99.9th percentile of quarterback performances. Again, this isn't exactly correct, but it is a nice interpretation that is close enough to the truth to be valuable.

After that, that's really it. Total quarterback rating is calculated by finding out a quarterback's expected points added and converting it to an estimated winning probability.

Why No QBR Calculator
It would be really nice if I could build a little widget and embed it on this page that would let the user enter a quarterback's stats and it would spit out that quarterback's total QBR. However, that isn't really possible in such a setting. Because the statistic relies on knowing the down, distance, time of game, and opponent for every single event, you can't build a QBR calculator just by entering in a few box score stats. In order to do that, you would need to basically enter by hand the play-by-play of the game. This is why I can't provide – and you won't find anywhere on the internet really – a total QBR calculator.

https://thedatajocks.com/passer-rating-qbr/

Originally posted by krizay:

How is Total Quarterback Rating Computed?Total Quarterback Rating is built on two ideas: measuring the expected points added by a quarterback and translating these expected points added to winning probabilities. Let's go through each of these components separately.

Expected Points AddedFirst, let's try to understand expected points added. Really, football and any other game is simple: score more points than your opponent. Then, if one could measure 'how many points' a particular player contributes to your team's total, then you could figure out definitively how much a player helps you win.

Each down and distance from each spot on the field in the NFL has an expected points scored on the drive. For example, if it is first and 1 from the opponents' 1 yard line, the expected points on the drive is almost certainly around 7. If it is 4th and 10 from your own 1 yard line, the expected points should be nearly 0. Computing the change in expected points from one play to the next lets us determine the 'value' of a play. Let's do an example.

It is 3rd and 10 at our own one yard line, the expected points on this drive are nearly 0. However, the running back rips off a 98 yard run to the opponents 1 yard line. Now the expected points on the drive is about 7. The previous play added 7 expected points to my team's total. If we determined that the running back was solely responsible for the outcome of that play, then the running back contributed 7 expected points to his team's total from that one play. We can compute a player's expected points added over all plays in the game this way to figure out how much a player contributes to their team's success. This is a lot like RE24 in baseball.

The first step in determining total QBR is determining the quarterback's expected points added over the course of the game. Because there are 11 players on each side of the ball, it can be hard to assign credit for the outcome of a play. In fact, entire articles have been written trying to assign credit for specific outcomes to one player or another.

However, for quarterbacks, the problem is often a lot simpler. For example, the quarterback gets credited for completing the pass and a few yards after contact, the rest is the receiver. A similar judgement and division of credit can be made for quarterback runs and sacks though that information is still proprietary to ESPN. In this way, we can calculate the expected points added by a quarterback. Now we need to convert this to a meaningful scale.

Logistic Regression for Winning ProbabilityAfter computing a quarterback's expected points added, we want to convert this number to something easy-to-digest. In particular, converting from expected points added to estimated winning probability is about as valuable as a conversion one could make. Why? Because then the numbers are easy to interpret.

A 50% chance at winning is a perfectly average performance; you'll win half the time you'll lose half the time. A QBR of 75 is significantly better. A QB with a season-long QBR of 75 should be expected to win 75% of their games if they play against league-average opponents. All else held equal, a quarterback with a 75 rating should lead your team to a 12-4 record. Most importantly, a perfect QBR of 100 is actually impossible to attain – as it should be! No matter how well your quarterback performs, you cannot ever guarantee a win because the other quarterback could always do the exact same thing.

How is the conversion from expected points to winning probability done? This is the perfect opportunity to use logistic regression. Logistic regression transforms 'continuous' predictive variables (like expected points added) into probabilities of an event happening. In particular, the logistic regression model fits a curve (the logistic curve) to existing data to translate from expected points added to winning probability. It is kind of like a least squares regression line or line of best fit in this way.

(As an aside, a good tool to learning logistic regression is this "hands on, practical" book that I've used before. Logistic regression is one of the top most important tools that data scientists and statisticians should learn. I consider it a "must know".)

While not entirely correct, if the data is sufficiently nicely distributed, one could actually think of total quarterback rating as a percentile of expected points added over all time. Then, a 99.9 QBR would correspond to the 99.9th percentile of quarterback performances. Again, this isn't exactly correct, but it is a nice interpretation that is close enough to the truth to be valuable.

After that, that's really it. Total quarterback rating is calculated by finding out a quarterback's expected points added and converting it to an estimated winning probability.

Why No QBR Calculator
It would be really nice if I could build a little widget and embed it on this page that would let the user enter a quarterback's stats and it would spit out that quarterback's total QBR. However, that isn't really possible in such a setting. Because the statistic relies on knowing the down, distance, time of game, and opponent for every single event, you can't build a QBR calculator just by entering in a few box score stats. In order to do that, you would need to basically enter by hand the play-by-play of the game. This is why I can't provide – and you won't find anywhere on the internet really – a total QBR calculator.

https://thedatajocks.com/passer-rating-qbr/

Now put this in your own words instead of copying and pasting it. Just because you can copy and paste something doesn't mean you understand it. Tell me what logistic regression and least squares regression line means without looking them up.

Time is up. You have no idea what you even posted. Atleast I can tell you in my own words how they determine passer rating.

Passer rating is a formula that is based heavily around completion percentage and to a lesser extent TD% and INT%.

Originally posted by YACBros85:
Time is up. You have no idea what you even posted. Atleast I can tell you in my own words how they determine passer rating.

Passer rating is a formula that is based heavily around completion percentage and to a lesser extent TD% and INT%.

Congratulations!

I don't know what all went into building my car. I just drive it. Do you walk everywhere because you don't know how your car was built?

I don't know how this PC was built. I just type on it.

I don't know how my beer was brewed I just drink it.

I don't know how they tabulate QBR I just use it.

I'm not one of those people that needs everything broken down for me.

Congrats to you though!

Originally posted by YACBros85:

I provided context to those stats. Out of those 105 yards in the first half, 16 of them came from YAC. Even if you take away the 45 yarder to Deebo, his efficiency stats in that game were still spectacular. So perhaps you missed that part of my post because you were so anxious to debunk my argument.

Data analysis is becoming more and more prevelant in today's NFL. Get used to it or atleast provide something we can all understand to back up your claims. I am all for watching film analysis but those who like to use film as proof never seem to provide any. Perhaps its because they aren't as fluent in film as they claim to be. Which is probably because they actually haven't a clue what they are even watching in the first place.

My argument isn't about using film analysis and not using stats. It's about you claiming to be a stat guy, but only actually using a select few of stats that are just as much team stats as individual stats, and using those selected stats to determine how an individual played.

If you're going to rely on statistics, grab as many of them as you can... not a select few. Use them in conjunction with film analysis. Doesn't have to be your own film watching either. There's a plethora of high level film analysis you can use in conjunction with stats, and what you think you see yourself.

Originally posted by YACBros85:
Time is up. You have no idea what you even posted. Atleast I can tell you in my own words how they determine passer rating.

Passer rating is a formula that is based heavily around completion percentage and to a lesser extent TD% and INT%.

"QBR isn't a perfect stat? No one even knows the formula used to come up with those numbers" Kinda put yourself in a 'Catch 22' situation there.

Fook the QBR. The best way to evaluate a player is to watch the film. Aka "the eye test"

Originally posted by tankle104:
Fook the QBR. The best way to evaluate a player is to watch the film. Aka "the eye test"

That is all I need. I know what I'm looking for. Could careless if my eye test doesn't compute to Yac's liking

Originally posted by krizay:

Originally posted by tankle104:
Fook the QBR. The best way to evaluate a player is to watch the film. Aka "the eye test"

That is all I need. I know what I'm looking for. Could careless if my eye test doesn't compute to Yac's liking

Stats help provide context and are important but the most accurate assessment comes from film, no question.

It's hard to argue a stance if all you're using are stats. You can manipulate stats to tell your own story often. It's important to watch the film and analyze the context.

It's easy to show off treys stats in the Texans game but when you break down his starts, it's the only game
hes throw a touchdown(s). They were also an awful team and only the other worst teams in the league (besides titans that year - division rivals) scored less. He's thrown an int every game, his completion percentage over his three starts combined is 55% etc etc.

his few starts have been rough. It def doesn't mean that's the player he will always be. He can and will improve, I'm confident in that. Just slowly but surely. I personally don't see him hitting top 10 qb in the league, but I could be wrong.

overall, we have an awesome qb room with Tons of talent and Kyle will make the best decision. I think it'll be Purdy unless he isn't healthy yet. When he is, I don't see him keeping Purdy on the bench. We will see though in a few months

Originally posted by krizay:
That is all I need. I know what I'm looking for. Could careless if my eye test doesn't compute to Yac's liking

And a stat like QBR, or a PFF grade, is exactly this with an attempt to put a number behind what they're seeing.

If a person is going to rely on passer rating, ypa, td percentage etc, they're going to run into problems judging an individual players performance as perfectly exampled by that Texans game. These basic stats make it look like he played great... more 'efficient' than the best QBs in the league if extrapolated over the course of the full season... but anybody who saw that game knows it was far from that level of performance, and if you don't ignore the stats that at least attempt to isolate for individual performance, that conclusion becomes clearer from not just an 'eye test' perspective, but a statistical one as well.