Didn't Ainge look to trade Rondo?
Is that too attached?
And what is worth more to a rebuilding team, bad contracts and draft picks in the 20's or cap space and a terrible team (thus having a chance at the better picks to build up cheap assets again)?
If Ainge was getting good offers for KG, Ray, Pierce or Rondo, I have little doubt he would be afraid to pull the trigger.
Just remember, it is easy for fans to say "just trade the guys and be good now". It is hard to actually pull that off.