But upon his arrival in Boston, the shooting guard was required to adjust his role. He no longer was asked to be the top scoring threat on his team but instead a complementary scorer and a defender.
Allen was effective on both ends during the season. And with his work against Kobe Bryant during the regular season and early in the NBA Finals, Allen is starting to distinguish himself as a strong defender.
In three games heading into Sunday night's Game 2, Allen had limited Bryant to 34 percent shooting and an average of 24.6 points - down from his season averages of 45.9 percent and 28.3 points a game.
"In past years I never thought of Ray as a great defender," teammate Paul Pierce said. "But when you look at the top scorers in the league, you never think of any of the top scorers in the league as great defenders because they're so great offensively, and I think that's been the case with Ray. I think since being here he's showed he's been more than a capable defender. ...
"He knows in order for us to win we have to play defense, and he's drawn the challenge of guarding Kobe, he's drawn the challenge of guarding [Atlanta's] Joe Johnson and he's stepped up that part of his play regardless of what he's done on the offensive end."
Allen said his improved defensive efforts are a byproduct of him buying into the Celtics' team philosophy.
"I've always been a pretty good team defender," Allen said. "The schemes that we use, the schemes that I've used my whole career, if you have one weak link, you all know the team defense is going to suffer throughout any games, throughout any season. I think here we have five guys at any time on the floor that are accountable, so it makes the job somewhat easier. You don't just point the finger and say it's on you; it's on all of us. One person makes a mistake. You don't compound it. We all key into each other."
Kobe is 'giddy'
Kobe Bryant has improved his image as a teammate this season, and from the Western Conference finale on, his coach has noticed a greater joy in his star player. At one point when talking about Bryant, Phil Jackson described him as "giddy."
"I think that that was really noticeable in the presentation of the Western Conference trophy. ... I thought he was very, very fun loving in that situation. I think you really see the true nature of Kobe Bryant with his teammates."
Bryant has been a jokester in practices this week, challenging his teammates to shooting contests and going so far as to bump them or toss balls into the air to deflect their shots to improve his chances of winning various competitions.
At the podium, he has shown a comical side.
When asked about the pressure of Game 2, he said, "I'd much rather have the pressure of this moment as opposed to having the pressure of deciding which swim trunks I'm going to wear in Bora Bora, the Gucci ones or the Yves Saint Laurent ones. I'd much rather have this pressure."
He defended teammate Pau Gasol's reputation of being less than physical against Celtics forward Kendrick Perkins but added: "Pau is not going to - you run into Perkins and Pau in an alley, you're probably going to go Pau's direction."
Asked about his teammates wearing his shoe, the Nike Zoom Kobe III, Bryant said, "Well, they all have an interest in jumping over cars. It intrigues them, so they wear the shoes."