Many people believe you need a top center to be a legitimate contender. So how will the Celtics get one within the next five years?
The Heat went to the finals 3 times without a "true center", and won two out of it
Not exactly true. Both Bosh and Birdman are hybrid power forwards/centers and were very good carving out space in the paint. That along with Ray's 3 point shooting and Lebron's athleticism were basically the reason Miami won last year.
They were able to space the floor out thanks in large part to their size.
Before that you had Dallas in 2011 with Dirk and Chandler, 2009 and 2010 Lakers with Bynum, Gasol and Odom and 2008 Celtics with KG, Perk, PJ Brown and Powe.
Granted, maybe there aren't many traditional centers in the NBA anymore in the mold of Bill Russell or Wilt Chamberlain, but basketball is still very much a big man's sport.