The Heat are a team built solely around their Big Three. If any one of them goes down with an injury, the Heat are completely forced to change their style of play.
In the 2012 Eastern Conference Semifinals against the Indiana Pacers, the Heat were able to shake off the series victory behind James' individual stroke of brilliance. The loss of Bosh wasn't too noticeable, except the fact that it forced James to play like a superhuman. James averaged 30 points, 10.8 rebounds, and 6.2 assits in the six games it took to eliminate the Pacers. He was simply better as an individual in the series than the Pacers were as a team.
Winning a series against an inexperienced playoff team without Bosh was impressive, but the Heat truly needed Bosh's presence versus the Boston Celtics in the Eastern Conference Championship. In Game 7, it was Bosh who made a career-best three 3-pointers, the last of which sparked the Heat's run that ended the game. Bosh's presence both allowed the Heat to spread the floor and play an effective style of small ball that the Celtics had a difficult time defending.
James, Wade and Bosh are talented enough that they are able to cover up for the rest of the Heat's deficiencies. When one member of the Big Three is unable to play, the other two are good enough to make up for the production in short-term situations. The Pacers were not a good enough team to make the Heat pay for the loss of Bosh. The Celtics were good enough to make the Heat pay. They would have beaten the Heat if it were not for Bosh's brilliant play in Game 7.
The Heat have been incredibly fortunate with injuries in the two seasons since Bosh and LeBron James decided to join Dwyane Wade in South Beach. There have been issues with Wade's knee, and, of course, there was the stretch in the 2012 playoffs when Bosh was out with an abdominal strain, but none of the Big Three's nicks and bruises have been too serious. The Heat's biggest contenders for the 2012-13 NBA championship all improved in the offseason. If the Heat are going to repeat as NBA champions, they will need all of the Big Three playing at a high level, including Bosh.
Before the start of the 2011-12 NBA season, Shaquille O'Neal famously said the Heat were led by a "Big Two," and not a "Big Three." O'Neal isn't necessarily the most respected critic (he recently said Andrew Bynum and Brook Lopez were both better centers than Dwight Howard), but his comments rang true with what many people believed—that James and Wade were superstars and Bosh was a fake star.
When Bosh was a member of the Toronto Raptors, he had more responsibility as the focal point of the team. Bosh is the same player he's always been. His statistics these past two seasons don't reflect that because he now plays with Wade and James. The bottom line is that the Heat don't need Bosh to be a superstar like Wade and James. The Heat need Bosh to be a presence in the low post to allow the Heat to play a style of basketball 90 percent of the NBA can't defend. With Bosh at center, Shane Battier at power forward, and Mario Chalmers and Wade at guard, James is allowed to effectively play a position that can only be described as point forward.
The 2012-13 NBA season will be the third go around with the Heat's Big Three. Never has their competition been tougher. The team the Heat beat in the 2012 NBA Finals, the Oklahoma City Thunder, will be better. Kevin Durant, Russell Westbrook and James Harden will not only improve their individual games, but they'll be hungry after tasting defeat in the Finals. If the Heat have any weakness, it's their size. The Los Angeles Lakers, arguably the new best team in the Western Conference, traded the second-best center in the NBA for the best center in the NBA. Then the Boston Celtics, less talented from a physical stand point but always capable of winning the mind battle, retooled and are arguably the best they've been since the 2008 championship team.
The rest of the NBA may have caught up to the Heat, which is why Bosh's presence is so important. Bosh proved that he's an important part of what the Heat do in the NBA Finals last year. When Bosh is in the lineup, it allows the Heat to play in a way that the rest of the NBA still has yet to figure out how to stop. The Heat will not win the 2012-13 NBA championship without Bosh. He proved so last season, and at some point this upcoming season, he will prove so once again.