Here are my 2 cents.
Caldwell as Derry pointed out as an "in game" coach is terrible. I think Caldwell recognizes that as from all accounts they basically had to drag him into the booth after they fired Cameron for the Super Bowl run. I personally hope he never makes a call during the game on Offense, Defense, or Special Teams. I hope if they hire Tressel his only job is to sit there with a button to press it every time Caldwell needs to use a time out.
Both O and D coordinators have saw recent success in the league building our weaknesses into strengths. I guarantee these guys see themselves as head coaches in the future and see the Lions as a stepping stone. Which either makes them brilliant or absolute morons. That being said they aren't here because they are married to scheme, hello tampa 2 and wide 9, or 3-4, 4-3 whatever. They aren't HC or OC/DC cast offs that failed elsewhere and are too stubborn to change. They are here to be the next Gase and Quinn which is how these guys move up the ranks. Lazer was interviewed to succeed and established OC in Miami just recently. Austin will tell Mayhew if Dennard or Gilbert or any other CB in the draft is worthy of their rank. He's been around enough good ones, and enough good ones at the early stages of their career to know.
Finally the hires show someone without a huge ego and a legitimate plan. I wouldn't be surprised if Dungy's fingerprints on it as well, as he seemingly has taken a vested interest in our success.