I partially agree. And leadership comes with experience and time. Very few young players carry their team in the first few years. Bird and Magic are the two that come to mind off the top of my head that did it. Lebron took a few years, Kobe took a few years, and even MJ took some time (maybe because he didn't have anyone for a while.)
The Celts main problem having watched this current team for nearly every game is that they can play stupid for stretches of games. When they abandon driving, go iso, and chuck 3s, it never works. Not only that, the get too careless at times. When locked in, they play amazingly well.
The Heat don't do much of that. They play controlled the entire game. Maybe it's because they have Jimmy and Dragon... and a bunch of other experienced players too like Crowder and Kelly O. They are definitely playing smarter than the Celts right now.
I'm a Celts fan, but I actually appreciate the Heat's style a lot. They play basketball the right way. When both teams are playing well, like the first quarter of yesterday's game, it's pretty fun to watch as a basketball fan.