In (almost) two full off-seasons with the Buffalo Bills, GM Buddy Nix and head coach Chan Gailey have focused on building competitive depth across their roster. The idea behind that is that a team that is competitive with itself will be competitive on the field (a quote paraphrased from Assistant GM Doug Whaley).
To this point, the Bills have accomplished that feat, even if some of the talent competing for playing time at certain positions isn't as high-quality as some Bills fans would like it to be. There are two spots on the team, however, that do not have that type of competitive depth - and they just so happen to be arguably the two most important positions on the offensive side of the ball.
It may not be a bad thing that Ryan Fitzpatrick is the team's unquestioned starter at quarterback. Fitzpatrick is the type of self-starter that doesn't need a guy on his heels to keep him fighting tooth and nail for his job.
Demetrius Bell also finds himself firmly entrenched as the team's starting left tackle. The only other players on the roster remotely capable of playing the blind side are Ed Wang, possibly Cordaro Howard and Jason Watkins. Those guys aren't going to play left tackle for the Bills next season unless they absolutely have to.