CINCINNATI -- Marvin Lewis' office gives away how much time has passed since he became head coach of the Cincinnati Bengals in 2003.

He sits at his desk with a TV in front of him, holding a clicker attached to the screen. Around him are pictures of his children and grandchildren (with another grandchild on the way this fall).

Lewis has been with this team for 15 years and things have certainly changed. The lifts once used to film practice have been replaced by cameras mounted on poles. The NFL has long made the transition from actual film to the digital world, and everything is instantaneous. Lewis can quickly pull up specific practice or game film from the comfort of his office.

But through the years, one thing has remained the same: Coaches will spend inordinately large chunks of their work week watching, critiquing and/or breaking down game and practice tape, just as they always have.

In between sharing stories of the creation of now-popular concepts such as the fire zone blitz, Lewis fast forwards and rewinds the video on the screen in front of him. This particular footage is from the Bengals' second practice of training camp. By this point, with another practice just an hour away, it already has been discussed with the players and shelved for another day.

Lewis explains what he looks for when he watches tape. By late August the team will be breaking down the tendencies of future opponents and how to exploit any perceived weaknesses. But in July, with a roster full of young players, he's looking for potential.

Lewis can quickly move between plays, which are organized on the right side of the screen and available with the click of a button. Plays that Lewis wants discussed in detail with the team are highlighted in yellow. Each play is available from at least two camera angles, if not more.

Lewis will watch the film of practice with the offense or defense and then switch. The coordinators then will pull out a few specific plays to discuss with the group. Position groups will have meetings throughout the day.

Lewis watches intently as one of his quarterbacks makes a nice throw over the middle for what should be a reception, but the receiver isn't looking for the ball, which falls incomplete. Those are the more obvious reasons.

The list of more subtle reasons that a play doesn't work are endless. Unnoticed in real time, they become obvious when Lewis stops to point out a particular player. A veteran offensive lineman has his stance too wide and is pushed into a teammate next to him. A wide receiver gets sloppy on his route running. A safety makes a mental error and goes to cover the tight end, leaving two men on one person and the backfield open.

On another play, a defender comes unblocked up the middle because there is a pre-snap failure to change the protection.

"You want to have as much time as you can," said quarterback Andy Dalton, who has the ability to change the protection call if needed. "I wouldn't say you have a ton of time ... probably 10 or 15 seconds at the most from once everybody is lined up and set. You've got to know what's happening based off different alignments. You've got to make the decision accordingly. And sometimes it doesn't happen until after the snap."

Dalton usually has 2-3 seconds at best to go through his progressions once the ball is snapped, and sometimes he doesn't quite know where the receiver is going to go. Lewis pulls up such a play on the practice tape, explaining that veteran receiver A.J. Green has the option to run a go route or break off inside depending on what he feels and sees from the defense.

Green breaks off the play inside and is open. Dalton briefly looks at him but progresses to another option. The play ends in a completion, but the best option would have been to go to Green. All of that has to be decided in just split seconds. To make it work, both Green and Dalton have to have a correct assessment of the coverage and what the defense is going to do.

"He's running his route based off a certain look and how the guys play him, and I've got a different view of the same guy," Dalton said. "But I think for the most part, I know what he's going to do before he even does it, just based on how the guys are playing him. I think that's just a matter of getting guys on the same page and making sure they're seeing the same thing you're seeing as a quarterback."

Green can make a cornerback pay for any sort of mental slip. Lewis brings up a play where William Jackson, an up-and-comer the coaches love because of his feet, flexibility and speed, is matched up against Green.

Jackson has the talent, but in just his second full year (his rookie year was lost to injury), he has some things to learn. Jackson's hand placement is a bit off, and as he reaches out with his left hand, it locks his hip. At the same time, he sneaks a peak to see where the quarterback is going to go with the ball. Green takes the opportunity to beat him on a slant route.

"That happens with young players," Lewis said.

Lewis' "play of the day" is a nice run by second-year running back Joe Mixon. Mixon's run is nice, but the play stands out for another reason only the coach might catch. Lewis points out how left guard Clint Boling makes the play happen. First, Boling assists center Billy Price by pounding at the nose tackle trying to come through the gap. Then he shuffles to the left and seals off the lane so Mixon can get through for a big gain.

"Everybody does their job," Lewis says.

Another good play has John Ross up against Dre Kirkpatrick one-on-one. Ross sells the skinny post and executes a beautiful double move to get separation from Kirkpatrick to run the slant-and-go instead. In a real game, that would be a touchdown.

It's an eye-opener to what Ross has the potential to do as one of the fastest players in the league. But like Jackson, he has some things to learn. Lewis points out some technique things on the play that Ross could have done better, but acknowledges he has the moves and speed to pull it off. If Ross stays healthy, those are small things that can and should be corrected by the end of camp.

In these early days of practice, the fundamentals impress the coaches more than the statistics. In a one-on-one drill, one quarterback has several incomplete passes that at first glance would suggest that he's having a bad day. Lewis explains why he actually wasn't.

One incomplete pass is attributed to a wide receiver breaking off the route too early. Two passes fall incomplete but sit just over the receiver's shoulder where the defender can't get to it. Even though the plays aren't successful, it's the kind of thing that will go a long way toward helping Lewis decide which quarterback will back up Dalton.

Lewis then goes through the same drill assessing the defense. He wants to see good fundamentals and technique. He also wants to see players apply what the coaches tell them and not continue to make the same mistakes.

Cornerback Sojourn Shelton, a young player competing for a spot, has great feet, and that's evident when he backpedals during the drill. Because he holds his backpedal steady and keeps each stride at the correct length without a hitch, he puts himself in good position to defend the ball.

Those are things that could help a young player make a team. Unfortunately for Shelton, he hurt his hand in the next practice and has to be put in a cast. Shelton will be out for an undetermined length of time, and as he and the coaches know, the longer he sits out the greater his odds to make the team become.

Others don't fare as well as Shelton in one-on-one drills. One has his stance too wide, which Lewis notes is a sign of a cornerback who tends to panic. Another takes a tiny stutter step as he moves backward, perhaps anticipating the ball too much. He tries to compensate by desperately grabbing at the receiver, a bad sign that the player has not corrected issues with his technique despite being in the league for several years.

Can film show if a player will be good right away? It can tell part of the story, but not the entire story. Price's first week of tape would've shown a lot of rookie mistakes with bad exchanges between him and Dalton for five straight practices.

The coaches haven't been too concerned. Price, the Bengals' first-round pick, didn't get to participate fully in OTAs due to injury. As Lewis watches Price on the screen, he discusses how the 22-year-old has shown maturity beyond his years. After spending part of the summer around him, Lewis isn't even sure the term rookie fits.

"He's not a rookie," Lewis said. "He's just new."