Something happens to Kendrick Perkins during the playoffs.

Always approachable and willing to give an interview before regular-season games, he blocks out everyone around him once the postseason rolls around. Perkins trades a smile for a scowl, listens to his iPod, and stares straight ahead as he walks from his locker toward the trainer’s room.

There are 82 other opportunities to be loose and talkative. During the playoffs, Perkins delivers his message on the court. 
 
As soon as the Orlando Magic defeated the Philadelphia 76ers in the first round, all eyes turned to Perkins. He would have to responsibility of stopping the Magic’s best player and a member of the All-NBA First Team, Dwight Howard. And he would have to do it alone.

For years Perkins was a true role player, always serving as a complimentary teammate to a more skilled post presence. Early in his career, Perkins looked to close friend Al Jefferson to take control. His evolution into a dominating big man became more unlikely playing in the shadow of Kevin Garnett.

Then, Perkins was tested. How would he perform without another threat in the paint? This season, the absence of  Garnett has revealed a more confident and aggressive version of Perkins, one that has been shutting down Howard on defense and burning the Magic with an impressive offensive repertoire.

“They played great defense tonight. They pushed me out, I didn’t get into a good rhythm,” Howard said following Game 1 of the Eastern Conference Semifinals, in which he was limited to seven points in the second half. “Kendrick kept a body on me and that’s what he’s supposed to do. I have a lot of respect for Kendrick and he makes me a better player, something I look forward to next game. Me and Pat (assistant coach Patrick Ewing) will watch film, see what I need to do so that it won’t be another night like tonight.”

Rather than Paul Pierce or Ray Allen, or even Rajon Rondo, Perkins has been the unsung hero of the Celtics-Magic series. He is averaging 9.8 points, 6.8 rebounds, and 2 blocks per game while shooting 57.4 percent from the field. Perkins is doing damage with a newly expanded offensive game -- post moves, hook shots, and midrange jumpers. The once overweight and clumsy-looking center has gained new weapons with the pounds he has shed.

“He’s improved a lot. Me and Tony Battie talked about that,” said Rashard Lewis. “(Celtics assistant coach) Clifford Ray is obviously doing a tremendous job showcasing his skills instead of just being a big man who rebounds and blocks shots. He has a mid-range jump shot, a jump hook that’s hard to get to, hard to stop. Just his overall talent, he’s picked up a lot of knowledge of the game.”

In spite of playing in the shadows of the Big Three, Perkins has outshined one of the most hyped players in the NBA on several occasions. His footwork and ability to get his shot away from the basket has made Howard’s limited postgame look one-dimensional. Not to mention, he is the only member of the Celtics who has proved capable of stopping Howard on defense. Howard, on the other hand, has the luxury of big men on the Magic bench to help contain Perkins.

“Offensively I’ve got to say he’s actually really good right now,” said Magic reserve Marcin Gortat. “He’s consistently scoring on the post, getting a lot of putbacks, and he definitely uses the chance when somebody on his team is driving and they kick the ball to him, he’s finishing around the basket very well. So he’s a pretty tough guy and obviously his aggressiveness on both ends is really good. And he’s probably one of the best -- if not the best -- guys who sets screens in offense.”

The downside of Perkins’ accomplishments is the glaring void left when he is not in the game. Short on big men, foul trouble is inevitable on any given night. On Thursday night in Game 6, his fifth foul in the fourth quarter came at the wrong time for the Celtics.

Down 70-67 with 6:52 left to play, Perkins was sidelined for the next five minutes to avoid fouling out. He headed to the bench with 15 points and 10 rebounds.

During that stretch, Howard grabbed four rebounds and made five trips to the free throw line. With Brian Scalabrine on the court instead of Perkins, the Celtics settled for jump shots and did not have a reliable option in the post.

Their inability to close the gap down the stretch led to their 83-75 loss. Perkins, who had a plus/minus of +2, was the only starter to did not finish the night in the red.

“It is frustrating,” Perkins said after the game. “It is important when you can close a team out. At one point in time, I think they were ready to lay down but we kept giving them hope. They got the fans back into it and got some energy. It just can’t happen on the road.”

Flashy players like Pierce and Allen thrive in the high-pressure situations of Game 7. This time, though, the big man down low cannot be ignored. Not only will the Celtics turn to Perkins to contain Howard, they will rely on his rapidly evolving offensive talents to spread the floor and own the post.

“I think to be an NBA championship team, you have to have a solid big man, and he’s a solid big man,” said Lewis. “He’s playing without Garnett this year but he’s doing a good job of controlling the paint and that’s something that a lot of teams don’t have. A lot of teams.”

The scowls, the focus, the intensity all lead up to Sunday night. Perkins will be ready to battle. He won’t talk about it before the game, though. He’ll just prove it on the court.