LOS ANGELES — It was last summer when Paul Pierce, Kevin Garnett and Ray Allen traveled to Detroit to see Rasheed Wallace. The pitch they gave him was simple: Come to Boston if you want a chance to win a championship.

There was something brilliant in their no-frills approach, for Wallace is a no-frills kind of player. He is something beyond old-school from his pregame attire — cut-off sweats and his customary AirForce 1’s — to his low-post game that is both beautifully skilled and also fundamentally sound.

He is a student of the brilliant basketball minds of Bill Ellerbee, Dean Smith and Larry Brown, and he has no use for the modern-day trappings of NBA stardom.

Wallace came to Boston for one reason, and one reason only — to play in games like Thursday night’s Game 7. The regular season may have been an afterthought for him, but the playoffs are what he plays the game for.

“Just hoop,” he said. “This is what I came here for. I love the situation.”

And through it all, this is why the Celtics got him. This is why the Big Three made their recruiting trip, which is not something they had ever done before.

“I remember going to Detroit this summer,” Ray Allen said. “Rasheed is going to help us during the playoffs, and this is the playoffs. This is as good as it gets right here. I look forward to it. There’s history going to be created tomorrow whether it’s good or bad for us. We have opportunities to make that determination.”

They will all be under the spotlight Thursday night. Pierce, Allen and Garnett all the way down to Nate Robinson and possibly even Shelden Williams, but the spotlight will fall heavily on Wallace, who will be asked to give the Celtics a low-post defensive presence in the absence of Kendrick Perkins.

“He’s been there before,” Perkins said. “That’s what makes it better. He knows how to go out there and compete. I just think he’s got to bring the intensity on the defensive end like he’s been doing. He’s been doing a great job on the defensive end and staying out of foul trouble and playing smart.”

Staying out of foul trouble will be job No. 1 for Wallace, who has racked up 20 personals in only 109 minutes of action. That breaks down to one every five and a half minutes. That’s fine in limited doses, but more than anything, the Celtics will need minutes from Wallace.

“You would hope, but he has been in foul trouble most of the games,” Doc Rivers said. “So, you have to go into the game anticipating that, really, and being ready to adjust if that happens.”

Wallace has been adept at guarding Pau Gasol throughout the finals. He’s busted out all of his veteran wiles, as he likes to call them, as well as brining a physical element to his defense. His offense has been scattershot, owing mainly to a balky back that has affected his shot.

Much of what will happen Thursday is also dependent on how much Andrew Bynum is able to give the Lakers. Rivers has preferred to matchup Glen Davis with Lamar Odom when he is in the game and he has stayed away from having Garnett and Wallace on the floor at the same time.

“Baby will be great,” Rivers said. “Just get back to just playing. I think Baby the last couple games has been doing way too much thinking. Baby is an instinctive intensity player. When he starts playing with thought, you know, that's not what you want.”

Rivers laughed at that, but he has a point. He needs Davis to just play with energy and emotion, because that is his best counter to the Lakers size, but Wallace needs to be cerebral.

“It’s my job,” Wallace said. “I got to be ready, know what I mean?”

He has been a constant tease this season, with a solid game followed by several head-scratching performances. He made no bones about the fact that he was here for April, May and June and that games with say, the Nets in January, didn’t hold a great deal of appeal for him.

The Celtics weathered his inconsistent outings, while grumbling privately along the way, but during the Cleveland series they finally began to see the player they thought they were going to get last summer.

“Yeah, I’m very happy at this moment that we have signed him, there’s no doubt about that, because we're going to need him,” Rivers said. “We’re going to need him big tomorrow. His experience will help. You know, and we’ll just see how many minutes he can go. Him and Baby and Shelden and Scal and Marquis, we’ll figure it out.”

The truth is no one knows what the Celtics will get out of Wallace in Game 7. He might be brilliant or he might be a foul-prone disaster, but he has a chance to make up for everything he’s done this season.

“We’re going to need everybody’s best [in Game 7],” Garnett said. “Sheed is just a piece of the puzzle and we’ve got to make it come together if we want to win.”

This is why they went after him. This is why they gave him three years. It wasn’t for long nights in December and January. It was for one game for everything. It was for Game 7.