While I was not a big fan of the teams he coached, I have enjoyed some of the leadership books written by Tony Dungy. One thing he writes about often is the importance of failure as a stepping stone to future success (provided one learns from past mistakes and remains open to trying new methods).
For those not familiar with Dungy's history, he was demoted from Defensive Coordinator back to DB coach by the Steelers in the late 80's, later became Head Coach of Tampa Bay and had a successful run in the 90's, but was fired from that job due to not winning a Super Bowl. He later won the Super Bowl as coach of the Colts. Dungy credits those setbacks with helping him re-evaluate, adapt, and finally reach his ultimate goal.
What does that have to do with Waddell? Maybe nothing. But I view it as a positive that he found much more success in his most recent role than he did with Atlanta. Unless he plans on reverting to things that didn't work for him in the past (which seems illogical and highly unlikely) then his Atlanta results don't concern me much.