Sometimes the simple answers are the right ones.
1. We are too injured.
2. We are old.
3. They are younger.
4. They are playing better.
5. Their important players are all healthy.
While I agree with some of this, the point is the Celtics were still in position to win this game and make it 2-2. Rondo hits a lay up. Maybe somebody, anybody sets a pick for Pierce on that last play, Paul desides to get up on James when everyone knows he's about to shoot a 3 because the clock is running out. I could go on, but the point is there was some bad luck, some bad playing (TO's) and some bad coaching that happened.
I agree with previous poster that there was no way Doc should have kept Rondo in the game in the 4th quarter. He was done. Baby played way too much and brought to little. And in spite of all this, with just a little luck it's a tied series.