Couple of observations about Smart and yes, I like his game and always have.
He is "reactive" in that his decision making when the ball is free is pretty much better than anyone else on the court. He can "see" a steal quicker, he can see what is going to happen with a loose ball quicker and, most importantly, he can get his body into position to make the play...quicker.
Opponents have to give him "some of their awareness" when he is up against them on the floor. He is a car wreck waiting to happen pretty much for every possession. I suggest he frequently takes an opponent out of his game.
There are plenty of NBA players who have these talents, I just think Smart uses them to significant effect.
Smart's commitment to a game makes his team mates on the floor better. His mates give more effort on defense and are more confident with Smart on the floor. intangible? I would ask his mates, fearlessness is catching.
On the court he leads by nature, not desire to lead or desire to be the recognized leader. With moments left in a game and mayhem is all around, Smart is NOT a part of this chaos, the game is too slow for him to fall behind. This was clear late in the third against the Heat and again in the 4th. Loose ball underneath and Smart makes one very hard move to the ball and saves the play. The Celtics eventually score on the possession and the cupcake Heat fold their chairs and go home.
I am old, there were plenty of great champions who "didn't score" a lot...or, who weren't known for their offensive game. These players transcended their weakness as all great champions do.
I think Smart has a chance of being one of these "great" players, he has along way to go, but his coach, whom I acknowledge as being highly competent has Smart on the floor for every second that counts...doesn't he?