Caldwell isn't a Pro Football Hall of Famer, but he strikes me as a lot like Mike Munchak. He's very low key, very focused on doing things the right way and well-liked by players.
I got to know him a bit while covering the Colts as part of the AFC South gig here.
He took a Colts team assembled by Bill Polian that had been very well coached by his predecessor, Tony Dungy, and quarterbacked by Peyton Manning to the Super Bowl at the end of 2009.
But it was hard to get a read on just how good a coach he was. His owner, Jim Irsay, tweeted out stuff while he was holding a news conference at training camp at least once and Caldwell was very much under the thumb of Polian.
They made him appear weak, which was a disservice. I believe he was unconcerned with appearances. But if he was concerned, I don't know that he was equipped to prove he wasn't weak.
A small illustration of what sort of guy he is: I traditionally write thank-you notes to guys who move away from the teams I cover. I sent them way late in 2011. Caldwell, who was in Baltimore as quarterback coach, actually wrote me back.