The third preseason game is when we get more than just a glimpse into the looming regular season. Starters play more snaps, which means we get to watch 30 minutes of quality football. Plus, we discover the players who may have a significant role for the team this fall.

Rookie linebacker Fred Warner had an excellent first start at linebacker for the San Francisco 49ers last Saturday and ended the afternoon with a team-leading five tackles.

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Good linebackers have aggression weaved into the microscopic strands of their DNA. Great linebackers, on the other hand, balance the rage with grace, patience, and brains.

Fred Warner has the tools to be an exceptional linebacker for the 49ers, and he displayed the gifts he brings to the defense and the team on the majority of his 34 snaps.

An overly aggressive linebacker can be a blessing and a curse for a defense. Indeed, there is not a defensive coordinator at any level of football who wouldn't want a linebacker unafraid to send himself into the scrum with the sole intention of destroying the ball carrier or lead blocker.

However, a good offense can exploit that mentality. So, adding a patient linebacker like Warner paid off in spades.

On the second play of the afternoon, Warner showed off his composure and his mental skill. Colts' rookie running back Jordan Wilkins took the handoff and tried to head to the right when Warner shot through the open gap to drop Wilkins for a three-yard loss.

Granted, it's just one play. But Warner played the simple run to perfection. He didn't commit early to the run, which would then make him susceptible to a play-action pass; he didn't drop back, which would then give up more ground to the lead block and the ball carrier.

Warner sniffed out the play and remained parallel to the line of scrimmage; he waited for the flaw in the blocking scheme and bolted through the gap to knock the running back into the artificial grass.

During the 49ers' second defensive series, the Colts ran the ball off right tackle, leaving Warner to cover the backside of the play. Once again, the 49ers were rewarded by Warner's calm demeanor. Rather than shooting the open gap at a sharp angle, Warner let the play develop and covered the backside edge. Suddenly, he found himself assisting in a tackle for loss when the ball carrier tried to change direction.

I also like how Warner doesn't deviate from his fundamentals. It's not shocking to see a linebacker give up his outside shoulder and fully engage the oncoming blocker. I've never understood the strategy, as it tips the advantage toward the pulling offensive lineman or the lead block.

Warner consistently kept his outside shoulder free and did not let an opponent get into his body. He kept attacking offensive linemen at arm's length and was able to quickly shed blocks by using a push-pull or twisting the opponent into a contorted position.

Brock Coyle, for example, has a bad habit of letting a lead block get too far into his body. Coyle has now taken himself out of the play, and the best that can happen is the running back makes the wrong read and ends up in a sea of 49er jerseys. At worse, Warner's ability to maintain leverage keeps the game at 11-on-11. At best, he can toss the lead block into the ground and shift the play in favor of the defense.

Of course, there are always improvements a rookie can make between now and Week 1. Warner was not great at blitzing the A-gap. Too often, he would get caught up in the scrum. I'd like to see him hit the gap with greater force and generate more pressures and hurries, rather than just create a muddled pocket for the quarterback.

Also, Warner had a few lapses in coverage, along with a few missed tackles. The coverage issues can easily be chalked up to the 49ers running a vanilla defense or just a miscommunication between the nickel defensive back and the linebacker. So far, plenty of men in the secondary have had problems with coverage, and I have a feeling these issues will be scrubbed away once the 49ers take on the Minnesota Vikings.

However, Warner slipped off a few open field receivers, which is slightly concerning. It looked like Warner was in stride with the ball carrier, but could not come down with a tackle. In his defense, sometimes those tackles are difficult. The body isn't in an athletic position, and with a myriad of tackling rules, a defender has to think of the legal way to bring down a runner. But it's his job to make plays in the open field, and he'll need to find a way to improve this part of his game.

Overall, I am looking forward to watching Warner this season, and I feel confident he'll step up to play his best football while second-year linebacker Reuben Foster is serving his suspension. Once Foster returns, Warner may fall back into a reserve role, but I still expect defensive coordinator Robert Saleh to use him frequently to give Foster and Malcolm Smith a series to recuperate.