For all the grief Doc gets about losing games due to substitutions and rotations, which I think is complete bunk, this game was a game he could have won with good coaching and good execution on his team's part.
But he lost any chance of winning the game with this bonehead decision. If the decision wasn't to foul immediately after the miss, then foul again and leave tons of time on the clock for a play to hit a three pointer and leave time on the clock in case you missed and got a rebound, then the team should have played to stop the Sixers and go for a winning basket, regardless of whether the Sixers had a foul to give.
This decision didn't lose the game for the Celtics, as Pierce did have a wide open three to tie the game except for that bogus foul, but it didn't maximize their chances of winning which is Doc's job. He let the team down with that coaching move.
Then again, the team let him down with their pathetic shooting and offensive execution for the entire second and third quarters.
Of greater concern to me was what appeared to be a conscious decision of the coaching staff to take the ball out of Rondo's hands to start the second half and have the offense go through Pierce. Rondo might have brought the ball up but just about every offensive possession went through Pierce to create or shoot.
Given how poorly he was playing, it was a bad decision that made a terrible offense even worse.