Dumb play by Rondo. He had the ball in his hands with 3 seconds left on the shot clock. He has to take that. Create a play and take the shot. He can't just hold and then pass it off without doing anything with the ball and screwing his teammate over in the process.
That turnover was Rondo's fault.
Also, it was a bad decision by Pierce not to take that shot on his dribble drive earlier in the possession. And Terry's fault to start running back before the shot went up and getting himself out of position and unable to get the three point corner shot up on the kickout. Bad possession. Lots of mistakes.