I don't think that's true. He traded a bucket load of picks for Ray Allen and Kevin Garnett. He worshiped the Nets draft picks, because they were all high lottery picks, and the only one he fucked up with was Kyrie, and I can't even put that on Ainge.
I mean, they turned into Tatum and Brown ffs. Or even his picks that are on the team now. Stephens is in a different place from Ainge, putting talent around a young core that already exists, as opposed to a full-on rebuild (which Ainge pulled off twice, btw, when other teams had their tanking 'process').