49ers mailbag: Why is Brock Purdy still doubted? Should we be worried about SF defense? Is Brandon Aiyuk a top-10 WR?

What's better than 4-0? 5-0, of course. And the San Francisco 49ers have the opportunity not only to improve to 5-0 on Sunday night but to do it at the expense of the Dallas Cowboys. Not only is Dallas a longtime rival, but they are a really good team with the potential to knock the 49ers off course. So this is a big game, and the 49ers need to come away with a big win.

We opened up the 49ers Webzone mailbag to see what was on your mind, so let's jump in and answer your questions.

If the 49ers get past the Cowboys, who is their first loss to? - DoctorWDS

Winning at Cleveland might be tougher than we initially thought, but some of that depends on whether or not Deshaun Watson is playing. Personally, I hope he does, because I think he's a terrible human being, and I'd love to watch him face this pass rush.

I would have thought the Bengals would be a difficult game to win, but they've been horrible so far. So has Minnesota, another team I thought might be good.

So I would say that if the 49ers beat Dallas on Sunday, the most predicted first loss would come in Philadelphia on December 3rd. But they probably will lose a game that they should win before December comes along. Or maybe they'll go 17-0!

Why do people still doubt Big (expletive) Brock? - Kenneth B.

Sorry, I had to censor you, Kenneth. There may be young eyes reading this.

I think there are three main reasons why people still doubt Big (expletive) Brock Purdy. First, he was the last player drafted. And there was a reason for that. Every team, including the 49ers, passed on him about seven times. So they apparently didn't see much in him. What it appears every team failed to measure, though, was the size of Purdy's heart. And I think people undervalued his head (how he sees the game, reads the field, and makes quick decisions that are mostly the right decisions).

The second reason is the weapons Purdy has at his disposal. Christian McCaffrey, Deebo Samuel, Brandon Aiyuk, and George Kittle are going to make a lot of QBs look good. Purdy is smart enough to use them, accurate enough to get them the ball so they can pick up extra yardage, and confident enough to make his teammates believe in him. He raises the performance level of everyone around him. But some will still say his success is due to his weapons.

Third, Kyle Shanahan is his play-caller. And Shanahan is perhaps the best in the league right now at scheming receivers open. Some people just assume that Purdy wouldn't be any good if he played somewhere else. Yes, Shanahan gets his guys open, but the QB still has to find them and then hit them. Purdy is able to do both consistently.

Trey Lance intel for Dan Quinn...valid concern? - Kenny S.

Normally you don't worry about this at all. Players change teams all the time. The fact that QB Trey Lance, who knows this offense very well, and now plays for the Cowboys, changes things a little. But not enough to move the needle to a place of valid concern.

And that's mainly because Dan Quinn, the Cowboys defensive coordinator, knows Shanahan very well. He knows his offense, he knows his players, his scheme, and his tendencies. Remember, Shanahan was Quinn's offensive coordinator in Atlanta.

Cowboys offensive coordinator Brian Schottenheimer spoke on Monday about Lance possibly being able to help the Cowboys offense when they go against the 49ers defense, saying, "Trey knows a little bit about what they're doing." But Schottenheimer, who also knows the 49ers well, from his days in Seattle, admitted that it's not much of an advantage.

"We can know exactly what they're going to do, because they don't do too much, and they're still really, really tough to go against just because they're so talented," Schottenheimer said. "We'll definitely talk to Trey. He knows a lot of the pieces going against them in practice, but it doesn't always help, as we learned yesterday."

Schottenheimer was referencing the fact that Ezekiel Elliott, who now plays for New England, wasn't much help for the Patriots when they played Dallas, even though the former Cowboys running back knows them quite well. The Cowboys won easily, 38-3.

And don't forget that the 49ers signed cornerback Anthony Brown, who spent seven seasons with the Cowboys. So it goes both ways. Brown will be able to help the 49ers about as much as Lance will be able to help the Cowboys, as far as intel goes. And that's likely not very much.

Does Kyle pull out all the stops to beat Dallas or not show all his cards against a team they expect to see again in the playoffs? - Doc

I think Shanahan sees this as a big game, and he sees this as a challenging game for the 49ers. He said as much on Monday when we spoke with the media.

As I mentioned in the previous response, these two teams know each other pretty well. I think the 49ers will show the Cowboys a few new wrinkles, and they may hold a few things back, as well. But for the most part, they know who each other is. It will really be all about executing.

Cowboys owner, Jerry Jones, certainly sees this as a big game. According to Jones, this game is a measuring stick to see where the Cowboys measure up against the team that Jones said is the Super Bowl favorite.

National hype/Media still doesn't have Aiyuk in the top 15 WRs? I see him as a top 10 WR easily, higher if he played on a pass-heavy team. Where would you rank him today? - Josh

The national media always seems to have a very slow learning curve when it comes to the 49ers. They're always behind. Aiyuk is a top-10 wide receiver, and by the end of the season, everyone else will see that.

He would likely get more national attention if he played for a New York team, or Dallas, or Kansas City. Maybe even Buffalo or Philly. Either way, the 49ers will have to figure out a way to extend Aiyuk this offseason. He's San Francisco's best wideout, and he needs to be paid as such.

Now that Aiyuk has a quarterback who likes to throw him the ball on a regular basis, he has a chance to have a huge season and earn his first Pro Bowl. Even though he missed one game, Aiyuk already has 17 catches for 320 yards and two touchdowns. He's averaging 18.8 yards per reception. He has not dropped a pass all season and has an 85% catch rate when targeted. Aiyuk is currently on pace to have over 1,800 yards receiving.

One of the most impressive Aiyuk stats, though, comes from Coach Yac, on Twitter (or whatever they call it): "Brandon Aiyuk has 17 catches this season. All of those resulted in either a first down or a touchdown." That's incredible. Those are like a super-sized version of Jauan Jennings' stats.

The 49ers defense has me very worried for Sunday night. Pep talk me into why I shouldn't be worried. - Scott B.

Steve Wilks is still learning his defense. I think they'll be fine. They still have a great pass rush, and right now, everyone on the defense is relatively healthy. Even the backups are coming in and making an impact (see Kinlaw, Javon and Burks, Oren).

Still, it does feel like the defense has struggled at times. This has mainly happened because the opposing quarterback has been getting rid of the ball quickly and not giving the pass rush time to get home. Dallas has been doing the same thing lately, but I wonder how long Dak Prescott will stick with that approach. A defense like the 49ers could rattle him enough that he gets impatient and makes some mistakes.

The other times opposing offenses have given the 49ers defense some problems has been when Ambry Thomas was in the game. When Thomas gets in, quarterbacks seem to be finding him for big gains. Whether Thomas plays or not will depend on how well Isaiah Oliver is playing, or what his matchup looks like. If the Cowboys have a bigger receiver in the slot, that's good for Oliver and the 49ers. Oliver is big and physical. If it's a smaller, quicker receiver, like Brandin Cooks, that's a problem for Oliver. And it could become a problem for the 49ers.

All you have to do is go back to the Pittsburgh Steelers' final drive of the first half to see the impact Thomas makes when he's on the field. Then look at the Arizona Cardinals game and see the scoring drive on which Thomas gave up a big play when he bit on a double-move, and then was part of the bad play that gave up the touchdown.

I reached out to Jonnydel, of Jonnydel's Football Academy, who I had on my show last week, to ask who messed up on that touchdown play. I thought it was Thomas, but not knowing what his assignment was on that play, I didn't want to call him out. Here was Jonnydel's take: "That's a mix of good design and poor execution. They ran a hi-lo on Thomas, who was in C-2 [coverage two]. Thomas bit hard on the underneath. He needs to gain depth and force a layered throw to allow [Talanoa] Hufanga time to close, or discourage the deeper throw altogether and then rally to tackle the underneath."

Thomas didn't do that, and the result was a touchdown for Arizona. He has the physical tools, but just makes too many mistakes. But I still think the defense will be fine. As long as Thomas plays little to none.

What is your dream player pick-up for the 49ers before the trade deadline? Mine is Patrick Surtain II. - DoctorWDS

My dream trade deadline pick-up would fall into one of three positions, as long as everyone is healthy:

• A cornerback (like Patrick Surtain II)
• A star offensive tackle (who can play right tackle now, and move to left tackle when Trent Williams retires)
• An edge rusher (who can be a legitimate compliment to Nick Bosa)

I put edge rusher last because I think the combination of Clelin Ferrell and Drake Jackson has been good so far. But then again, if you were able to add another star at that position, this defense would be even more scary than they are now.

Colton McKivitz has been decent at right tackle so far, but it's matchups like in week one against T.J. Watt, and matchups like this Sunday, against Micah Parsons, that make me nervous. And these are the kind of pass rushers you face in the playoffs. I realize everyone has problems with guys like that, but having another solid tackle would make me feel better. And isn't that what this is all about—making me feel better?

I put cornerback in the top spot because I don't completely trust Oliver or Thomas. And neither does the coaching staff. If the 49ers could get a top-rated corner like Surtain II, they could move Deommodore Lenoir inside and play the new guy outside with Charvarius Ward. That would make this secondary much better. Or find a really good nickel corner, and keep Lenoir outside. (By the way, I'd be shocked if the Denver Broncos decided to trade Surtain. And I'm guessing he would cost a lot. Probably more than what the 49ers gave up to get McCaffrey.)

One potential trade could be with the Carolina Panthers. As Brad Graham notes, Carolina has no first-round pick in 2024.

And I like where Jason Aponte's head is here, throwing out names like Brian Burns and Jaycee Horn. Both would be nice additions to the 49ers defense. But again, I doubt Carolina will give up one of these guys. They're a rebuilding team, and those two defensive players would be nice to build around.

That's all we have this week. Be sure to check back next Monday when we reopen the 49ers Webzone mailbag.