I hate that "run the clock down" philosophy. I mean, I definitely understand it if there's a 2-second difference between the shot and game clock at the end. It's always a great idea to bring the clock all the way down in that situation if you're winning. But when there is about a 5-6 second difference, and you're up by 1? To hell with waiting around, you gotta take advantage of any opening you can get, and that's exactly what Dirk did. I'd much rather have a 3 point lead with 15 seconds left in the game than a 1 point lead with 6 seconds left.
I agree this is what happened. If Miami's D was set, it wouldn't make sense for Dirk to go early and Van Gundy would be right. However, I think Dirk saw that Miami's help defenders around the rim were kind of asleep (probably not expecting him to make a move that quickly), so he drove and got a layup. Good move in that situation. However, it may not be a good move if Miami wasn't asleep with their pants down.
What keeps that shot from being a bad strategic choice is because Dirk converted it and Dallas ended winning on that shot. JVG is right, smart money is that you wait another few seconds before you go. If you play 10 games it probably costs you a couple games. Dirk himself said at the presser that he went early because he saw an opportunity. When you coach, you coach the team for the proper tactical choices. You drill drill drill it into their heads, because when the adrenaline is pumping, fatigue is going, and the other team is reacting you need that repetition. Given all that, the player makes decisions based on the circumstances, but your work as a coach is to drill in the right sequence. Keep in mind that the game is just about execution. Honestly basketball isn't a strategic game like football or speed track, it's about execution. You miss you lose, you make you win, regardless of all the best plans you lay. Game 3, Dirk makes it, or Bosh misses and Mavs win. Game 4 Dirk misses or Miller makes it and Miami wins. JVG isn't wrong, what makes that play a smart one is simply that they won the game with it