WALTHAM, Mass. -- Jermaine O'Neal essentially had his choice of Big Threes this offseason. But stressing that winning -- and winning right now -- was the most important thing to him at this advanced stage of his career, O'Neal chose to sign with Boston rather than remain in Miami.
"I knew what they were trying to do [in Miami], and I could have re-signed back with those guys," O'Neal said of his former team, which recruited LeBron James and Chris Bosh to join Dwyane Wade this offseason. "It comes down to fit; it comes down to personality and the style of play. Boston has that all for me.
"This was the most important choice that I've made in my career, the first time I've been a free agent in my 14 years. It was very difficult, but over the next two years, I needed to be where it's strictly about winning now and not worrying about chemistry or worrying about anything else. It's just about coming in and helping the team win, being involved in something great.
"I felt like the Celtics have the best team. I had a chance to re-sign back with [Miami], but I thought this was where I was meant to be."
O'Neal passed a physical Wednesday before officially inking a two-year deal to join the Celtics. He will receive the full midlevel exception of $5.76 million this season and earn a total of around $12 million.
While O'Neal is just 31 years old, he's got 14 years of NBA wear and tear on his tires, and he noted his plan is simple: Win a title in 2010-11, repeat in 2011-12, then ride off into the sunset.
While that's a mighty lofty goal, it's not unfeasible with a Boston team that's been in the NBA Finals in two of the past three years. And that's exactly why O'Neal is here.
"[The Big Three] are at a position in their career, and I'm kinda at the same position," O'Neal said. "Obviously, those guys have a ring, but they want another one. I don't have a ring and I want one.
"Their hunger, their focus are at a different level. There're other good teams out there that I looked at that I could compete for a championship with. But these guys just came off an NBA Finals appearance, and in 2008 they won one. They know what it takes to get there, and really, when thinking about it and talking to my family, we thought this was the best fit for me."
O'Neal admitted his decision ultimately came down to Boston, Denver and Dallas. He wasn't particularly keen on the idea of coming off the bench, so the fact that Kendrick Perkins will start the season sidelined as he recovers from ACL surgery on his right knee might have actually helped Boston.
O'Neal is pegged as Perkins' replacement to start the season, and he noted he's fine with sliding to a supporting role when Perkins does return from injury. In fact, O'Neal seems genuinely excited about the potential to spend time at power forward, potentially spelling Kevin Garnett off the bench and sharing court time with Perkins.
"This is something I want to talk about now and not talk about anymore during the season: When [Perkins] comes back, it's his position to have," O'Neal said. "I'm just here to do my job. I'm not trying to step on anyone's feet or cause any issues. I'm just here to win; that's what it boils down to.
"There were a couple situations where I talked to teams and I probably wouldn't have wanted to back anyone up. But this situation is proven. Why come in and mess up something that's already proven?"
O'Neal seems familiar with the fact that Boston's starting five from the past three seasons is undefeated in postseason play -- when healthy. He's perfectly fine with being a sixth or seventh (or 12th) man if that continues.
When word trickled out last week that the Celtics were on the verge of signing O'Neal, the move was met with a lukewarm response among some Celtics fans after O'Neal's mediocre play against the Green in the first round of this past season's playoffs.
O'Neal didn't want to use injuries as a crutch then but disclosed his ailment Wednesday. He said he got kicked in his left ankle during a regular-season game against the New York Knicks on April 11. O'Neal played only 17 minutes that night, then sat out the Heat's final two games of the regular season.
In Game 1 versus Boston, O'Neal finished with 3-of-14 shooting with eight points and nine rebounds over 32 minutes. He went on to average a mere 4.2 points per game on 9-of-44 shooting during the series, his playing time limited to an average of 21 minutes over the final four games of the five-game set.
"My ankle was extremely swollen, but, to me, if you're suited up and you go out there, you're telling your team, you're telling your followers, that you're ready to play," O'Neal said. "Whatever excuse you have should be kept in the locker room. I chose not to talk about it, because it didn't really matter. I still felt like I could help the team. Unfortunately, I wasn't able to do it."
O'Neal has been dogged by injury concerns since his final seasons in Indiana but suggested he played through a damaged meniscus for as much as two full seasons with the Pacers before finally having surgery.
He deemed himself in full health now for both his ankle and knee, heaping praise on both the Toronto and Miami medical staffs for helping him rehabilitate and strengthen the knee. He plans to follow their same regimen this offseason to remain in the form that allowed him to play 70 regular-season games last season, his most since the 2003-04 campaign.
"He's versatile, he can shoot, he can catch and finish, and he can score in the paint with his left hand or right hand," Celtics president of basketball operations Danny Ainge said when asked what he likes about O'Neal.
"We're very excited to have him here. He brings a great deal of leadership and knowledge. I think his game is a perfect fit and complement to the guys we have on the roster."
That didn't prevent Boston's medical staff from giving O'Neal a full inspection and quizzing him about his knee injury as they ran him through physical examinations Wednesday at New England Baptist Hospital. Doctors even asked him whether he had ever suffered an ACL tear in the knee.
O'Neal stressed he had not, but when his introduction got delayed by nearly two and a half hours, reporters couldn't help but have flashbacks to Raef LaFrentz and his knee woes. O'Neal and Ainge quickly squashed any worries about his health.
"We checked him out thoroughly today, with a physical and his medical records from the past," Ainge said. "He's only 31 years old today; he'll be 32 in training camp ... but we're not concerned about [his health]. No more than any other player."
O'Neal said he wants to play only two more seasons, if all goes well. He has two children -- daughter Asjia and son Jermaine Jr. -- with whom he wants to spend more time and be active.
That's why he needs to enact his plan.
"I'm not worried about injuries; I'm not worried about anything," said O'Neal, who suggested he's learned how to keep his body in peak form even as he gets older and his physical skills deteriorate. "I feel, physically, I could play five more years. But hopefully we win next year and win the year after; then I can walk away."
Chris Forsberg is the Celtics reporter for ESPNBoston.com. Follow him on Twitter.