As far as Sanders, he provides a huge boost when he's playing, and he was an enormous part of the Colts' Super Bowl run in 2006, but he's been in the league for six years, and has played a total of 47 regular-season games. As good as he is, do the Colts want to keep entrusting their defense to a guy who averages half a season on the bench?
And while we're on the Colts' problems, Joseph Addai clearly is not the back they hoped he'd turn out to be. On the season, he's averaging 3.3 yards a carry, and has averaged more than 4.0 in only two contests. (The yards-per-carry figure has gone down every year Addai has been in the league.) The Colts don't need a Michael Turner who can carry an offense with 30 carries, but they need a guy who can help kill a game in the fourth, get them to third and short on his own, and can move the offense for a series or two if Manning is off or if the conditions are bad. Especially now that the top-ranked defense is banged up. Addai is still a weapon catching passes, but if he's their best option running the football, the Colts offense could be in trouble. If Donald Brown is healthy, he should start getting the lion's share of the carries.
So much complaining, you'd never know they were undefeated.