Don't blame it on Paul Pierce's missed three-pointer.

Don't put it all on Glen Davis' offensive struggles.

Don't point the finger at Kendrick Perkins' six fouls.

The Celtics' Game 4, double-overtime loss to the Bulls was not about their starting lineup. They would have been in a better position to win if they could rely on their bench, which was outscored 40-11 by just two Bulls reserves. The Celtics looked like a five-man team with nowhere to turn to.

The Celtics had managed to adjust to the void left by Kevin Garnett in the second half of the season. Glen Davis transitioned in the starting lineup and Leon Powe fought his way back from a mid-March knee injury to give the Cs another reliable big man off the bench. But on Sunday the combined absences of Garnett (knee) and Powe (ACL) were too much to overcome.

Kendrick Perkins had played one of his best first halves of basketball all season. He was getting to Joakim Noah and carrying the Celtics down low as Davis struggled to find his shot. But it's no secret that Perkins is foul-prone. He was called for his third personal early in the third quarter, forcing Doc Rivers to turn to his depleted second unit of big men.

Unable to rely on Mikki Moore, who has struggled to adjust to the Celtics system since joining the team in February, Rivers turned to Scalabrine. While Scalabrine did all the dirty work, playing him at the five spot meant Davis (4-16 FG) had to stay at the power forward. Without having Powe available, Rivers had to play Davis despite being an offensive liability in through the first three quarters.

Both Perkins and Scalabrine eventually fouled out. If Rivers had more options on the bench, Perkins would not have had to play 40 minutes in regulation (he averaged less than 30 per game on the season). By the time the Celtics entered double overtime, they were forced to go with a smaller lineup.

This loss wasn't just about the Celtics big men. No one from their second unit backcourt stepped up, either. Bulls guard Kirk Hinrich scored 18 points off the bench. Celtics guards Eddie House and Stephon Marbury combined for just eight. Tony Allen, who was put in for a defensive stop on the Bulls final possession in regulation, lost Ben Gordon on the inbounds pass. Gordon sent the game into double overtime with a three-pointer.

Now the Celtics head into Game 5 run down and overworked. Time management had been a concern all season with injuries and in Game 4 the Celtics starters had no choice but to stay on the court. (Rajon Rondo played a game-high 55 minutes while Pierce played 52.) The Bulls, on the other hand, were assisted by 43 minutes from Hinrich.

The Celtics have the talent in their starting lineup to defend their title. But they needed their bench last season to get it done even with a healthy Garnett. The Celtics have to be more than a five-man team, especially when their biggest man of all is out.