The Lions wanted a QB guru for Stafford and they got Peyton Manning's QB coach. Its hard to be upset about that.
There will always be talk that he only succeeded as a HC because of Manning, but Manning has been in the league 15 years. If it were so easy to just ride Manning to super bowls, how come all the other coach's he has had didn't get there every year?
Manning has only been to the super bowl twice in 15 years. One of those times was with Caldwell. That means something in my opinion. In the last 5 seasons before this year, Manning lost in the 1st round of the playoffs 4 of the 5 times, with 3 different HCs (Dungy, Fox, and Caldwell), and the one year he succeeded wasn't under Dungy or Fox, it was under Caldwell. So I think this guy deserves more credit than he gets for Manning's success.
Also, it should be remembered that the 2-14 season wasn't just because Manning was inactive, the Colts ownership was also openly tanking for Luck. Its telling when their GM changes 35 players on their roster that following summer, that the ownership knew it wasn't just about Manning. So to blame that all on Caldwell would be inaccurate. That was just an old team whose run had come to an end & father time had caught up, and ownership decided it were better to lose for a high pick and rebuild.