I'm not a big fan of the blame game because this is a team game and you win and lose as a team.
...that said, it is human nature (or maybe just fan nature) to look for someone to point at and say "you should have stepped up more." I know many of you will want to voice your frustrations at said people, so I'll post a specifically worded poll and let you comment below.
Bonus Link: See postgame reactions from the Celtics here.