The second discipline is between Stafford's ears. I think everyone understands that Stafford has as much physical talent as any quarterback in the league. What he hasn't developed is the mental acuity to exploit his physical advantages. He recently told the press that he doesn't need a quarterback guru, to the dismay of - well - everyone. Caldwell has a great record with quarterbacks. He was quarterbacks coach with Penn State while Kerry Collins was there. While he didn't have much success with his QBs at Wake Forest (notable only for Brian Kuklick) his time with Peyton Manning cannot be overlooked. While it can be debated whether Caldwell influenced Manning's development, it cannot be debated that merely being in the presence of Peyton had to have helped Caldwell. I think all Raven fans would agree that not only did he represent an enormous upgrade at OC when he came, but that he also brought something to Flacco or at least that he was able to deliver the offense to Flacco's skillset. If he can duplicate this in Detroit, the team will be in the playoffs annually.
5. He's black. This point really can't be underscored enough. Black head coaches in the NFL have an excellent record overall. The list is astonishingly short, of course, but also astonishingly successful. Not count Fritz Pollard in 1921, and not counting interims, there have been 15 black NFL head coaches. Of those 15 only Romeo Crennel, Mike Singletary and Raheem Morris failed to take their teams to the playoffs at least once. Crennel and Morris both had 10 win seasons, Singletary an 8 win season. Flores, Dungy and Tomlin each won Super Bowls while Lovie and Caldwell each lost one. Additionally, Shell and Green (twice) took their teams to conference championships.
6. Finally, he's learned. I can't prove this of course, but I assume that everyone learns and that Caldwell couldn't have 'won' the interview without displaying skills that he may not have had in the past. Stafford (and Bill Ford Jr) sat in on Caldwell's interview and Caldwell proceeded to break down film showing Stafford where he could have made better decisions in certain spots. While Stafford may publicly deny the need for a quarterback whisperer, everyone welcomes a mentor when the situation presents. If Caldwell can be a mentor to Stafford, if Caldwell can get Stafford to take that next step to disciplined player, then this hire will be a success and so will the team.