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* Remember the good times: The knee-jerk reaction for some Boston fans will be anger at Allen for choosing a primary rival over coming back with the rest of the Celtics' core in hopes of toppling the East's new champion juggernaut. After that initial sting wears off, hopefully those same fans will reflect on five memorable seasons that included the NBA title in 2008 and Allen's becoming the NBA's all-time 3-point king last season in a Boston uniform. Without the draft-night deal that brought Allen to Boston in the summer of 2007, there likely wasn't Kevin Garnett behind him to form the Big Three and set into motion this era of success.
* Still tough to swallow: For Allen, there was no wrong decision here. In a way, he should be commended for taking a much smaller paycheck in order to finish off his career on his terms. Alas, he will appear the lone dissenter as the Celtics put the band back together for another run. And he's signing with the team that ended Boston's season each of the past two years. It will be interesting to see what sort of reaction he receives the first time he steps back on the Garden floor next season. Maybe by then, it'll be easier for Celtics fans to swallow.
* A good fit for Allen: After watching the likes of Mike Miller and Shane Battier fire away from beyond the arc throughout the playoffs, including in the Eastern Conference finals against the Celtics, Allen has to be downright giddy at the thought of the looks he'll generate as LeBron James and Dwyane Wade attack the basket. For a player with a diminished ability to generate his own shot, the Miami offense will allow him to thrive even at an advanced age. The biggest thing for Miami is figuring out a way to integrate him in the offense when it already has Wade at the shooting guard position to start and end games.
* The Celtics had insurance: Boston truly wanted Allen back, even if it knew it was overspending with a two-year, $12 million offer. The signing of Jason Terry earlier this week takes a bit of the sting out, as the former Sixth Man of the Year will assume Allen's role as bench scorer. Still, it's tough for Boston because it owned Allen's Bird rights, which gave the Celtics the ability to offer more than other contenders in order to retain his services. With his departure as a pure free-agent signing by the Heat, it prevents Boston from even utilizing him in a sign-and-trade situation to bring back an asset (something that might have existed with another team). The Celtics cannot turn around and use the $6 million they had offered him to attract another free agent, as they have only the bi-annual exception ($2 million) left to offer an outside free agent above the minimum.
* Can Allen stay healthy? The one lingering question after Allen battled bone spurs late in the 2011-12 campaign is whether he'll bounce back. Celtics president of basketball operations Danny Ainge seemed to believe he would, and the Heat are banking on that by offering him three years at the full value of the taxpayer's midlevel (a total of $9 million).
* Honestly, it was time to move on: Fair or not, Allen was always the third wheel of Boston's Big Three with Paul Pierce and Garnett getting the bigger share for Boston's success (and rightfully so, but Allen did his job so efficiently, his contributions were sometimes overlooked). The fact that Allen clashed with point guard Rajon Rondo -- even if it rarely manifested itself on the court -- didn't help matters, either. With Allen's name swirling in trade rumors at each of the past two deadlines and his having moved to the bench role at the end of last season, Allen likely felt stung and a bit unwanted. Miami offers him a chance -- maybe even better than Boston can offer -- to chase another NBA title and without the bitter winters that prevent him from getting on the golf course with much frequency.
* Go ahead, Celtics fans, vent: We know a lot of you are angry. Utilize the comments to scream and yell (and, once you've settled down, feel free to reflect on those five years with your memories of Allen in green).