The first reason why it's not going to happen is because the Heat's target on their back is only going to get bigger as the season goes on.
Kevin Garnett, former teammate and friend of Ray Allen, has already come out and said that he's "cut ties" with Allen and that he "doesn't have Allen's [phone] number" anymore—as reported by Gary Dzen the Boston Globe.
It's clear that Allen's past teammates aren't too fond of him leaving for the sunny beaches of South Beach, and that means that when the Celtics face off against the Heat, the stakes are going to be that much higher.
Speaking of Allen, the fact that the Heat now have to adjust their roster rotation with Allen and Rashard Lewis on the depth chart is going to complicate things as the 2012-13 season gets under way.
Sure, having more talent is never a bad problem, but in the 2012 NBA Finals, the Heat had found a rotation that worked extremely well for them that consisted of Mario Chalmers at the point, Dwyane Wade and Shane Battier on the wing and LeBron James and Chris Bosh holding down the frontcourt.
As the old adage goes, "if it ain't broke, don't fix it." Well, the Heat have done just that by adding more talent to an already competent and productive roster.
The big issue isn't going to be making sure players get the looks and touches they need to succeed. Guys like LeBron, Wade and Bosh will find ways to get the ball the amount that they need to.
The biggest question will be if chemistry can be established between the new players on the Heat's roster.
During the Heat's 2011 failure in the NBA Finals, we saw just how important chemistry is, and if the Heat take a step back this season in the chemistry department, they aren't going to even get close to repeating as NBA champions.
While LeBron has what it takes to win the 2013 NBA MVP and earn another round of All-Star and All-NBA first-team honors, he can only win another ring if the Heat have chemistry, and Allen is going to keep them from doing that.
Allen isn't a bad teammate, and he's intelligent enough to figure out how to fit in the Heat's system, but just the fact that the Heat are going to have to adjust their already successful rotation is a major reason for concern for the Heat heading into the 2012-13 season.
Allen's inability to help the Heat win the 2013 NBA title isn't going to be because of him, it's going to be because of head coach Erik Spoelstra's inability to fit him, successfully, into the Heat's rotation.
Spoelstra will struggle to fit Allen, and even Rashard Lewis, into the Heat's rotation because he doesn't do well making effective alterations to his bench rotation.
The Heat have a more difficult road ahead of them than many want to admit, and with teams like the L.A. Lakers, Boston Celtics, Denver Nuggets and Oklahoma City Thunder only getting stronger, the Heat's path to the 2013 title will be a tough one.