BOSTON — Reinvention, thy name is Celtics. Everything old is new again.

New Perk (Kendrick Perkins) new KG (Kevin Garnett), new Big Baby (Glen Davis) and new Sheed (Rasheed Wallace).

OK, not so fast. Let's scratch that last one — that would be getting a little carried away on the so-called rapid road to maturity.

First came KG, who seemingly has reversed the clock after a miserable showing in Game 1, abruptly, turning his fortunes around by Game 2. The Finals are tied 2-2 with Game 5 Sunday in Boston.

"It was important to me to feel like I was actually in the game," Garnett said on Saturday about Game 2. "I'm down on myself about being proactive and being in the game and doing multiple things."

Then there's Perkins, teetering on the edge of a one-game dismissal, which could come via a seventh T, but, so far, handling the balancing act quite nicely.

"I thought Perk did a great job of walking away (from Pau Gasol)," Celtics coach Doc Rivers said. "It's clearly a new Perk. I hadn't seen that side of him."

Finally we have Big Baby, who broke his thumb in a scrap with a childhood buddy just before the season opener, which forced him to miss the first 27 games.

It would be a stretch to say Baby grew up in Game 4 — who could say that about a drooling, screaming lively force? But his energy and scoring off the bench in the fourth quarter prevented the Celtics from falling behind 3-1 in the series.

Point guard Rajon Rondo revealed he had a few choice words for Davis when he learned of the injury.

"I was very angry at Baby," Rondo said. "I was pretty (hacked) off. He's very vital to our team and that kind of hurt us. I called him and told him a couple of things. I can't say it right here."

Rondo reported that Davis took the admonishment in the proper spirit, and said he thought Davis would not make the same mistake, adding, "He's still Big Baby."

There is, understandably, some guarded optimism about the progress Davis has made so far.

"He still has to turn corners," Rivers said. "Honestly, he has to turn a corner (Sunday). Can you have a big game and then can you have another one? And that's for all of them. Nate (Robinson) and Tony (Allen), as well. Are you going to be a one-hit wonder? What is it going to be?"

Lakers center Andrew Bynum, who had his right knee drained Friday, said he expects to play in Game 5. That should help LA's effort against Davis and Perkins.