The Perk trade. He traded away the mojo that team had because it really miffed the guys in the locker room. Doc lost that team, at that point. Green came over and was a complete non factor in 2011. Then he had his heart ailment and disappeared for a year.
It was an awful trade. Ainge should have just let the team go for that chip one more time together and then let Perk walk if Perk got a big, ridiculous offer.
Funny enough, in future years, Ainge let guys walk rather than trade them to get something from the players not returning. Did this trade teach Ainge, sometimes you are better letting teams play things out rather than dumping a guy to get something because you know you won't be bringing the player back at a much higher price? Maybe, maybe not.