Oftentimes depth is overlooked in the NFL by the pundits and fans, but it often is the difference between celebrating a Super Bowl and not making the playoffs. A perfect case in point is the Carolina Panthers. Two seasons ago they made it to the Super Bowl and the next season missed the playoffs due to a rash of injuries. They actually had good depth at the positions they ran into problems with, but the injuries kept on coming and they ended up not being able to defend their NFC championship.
It's a very thin line to walk for football coaches trying to get their starters as many snaps as possible while also getting the backup ready for action if push comes to shove. What's hard about keeping backups ready is it's so hard to get them reps during the week because a coach wants his starter as prepared as possible. I know when I was in the league I was greedy about my snaps and tried to keep the backup off the field as much as possible. I didn't want him to go out there and play well or show something to the coaches that would give them any confidence in his ability. From a starter's standpoint, it's the one thing you regret, and I stress to everyone, particularly quarterbacks, to stay healthy and allow yourself a chance to practice and play. Once that window of opportunity opens up, then your job becomes tougher because you're in a competition.
I knew then that no matter how much a backup reads the playbook or is a film junkie, he's still not going to be anywhere near as ready as the starter. Watching film and reading the playbook and expecting to be ready is akin to my watching tapes of Andre Agassi and reading a book that he wrote and thinking I'd be ready to play him. There's not enough mental preparation to get a player ready for the physical part of the game.