I see it like this - his skill level really isn't better than those "cheap tactics", because he understands he doesn't have the ability to score at a regular rate without them.
Plan A - look for an easy opportunity to score. Plan B - look to get a whistle. That's the gist of his game. He only started generating consistent offense in that 3rd quarter because he identified easy scoring opportunities and capitalized on them. It's what he does best. It's the same thing Karl Malone used to do. It's why he employs those cheaps tactics in the first place, because when things get tough or he identifies that he doesn't have a high chance of scoring he resorts to using them. It's why he cherry-picks, it's why he typically drives when a player is out of position, or there's a weak rim protector, or if he can bait a defender into swiping at his hand/ball. If there's an easy opportunity to score, you best believe he'll take it.
Now there's absolutely nothing wrong with that, obviously. And that's what he should be doing. However, those opportunities come around less often in the postseason, not only because teams tighten up their D and gameplan meticulously, but as we all know the officials let more contact slide. Once he's left without an abundance of regular easy scoring opportuniuties to take advantage of, and doesn't get the calls he usually gets - his and his team's offense suffers, greatly. It basically stops the Rockets from going on runs and it stops them from continuing runs once on them. It's why he has such erractic shooting games/periods, and you never feel like he's ever in control of the game. The amount of damage this does to the flow of the offense is immeasurable.
If you only look to score during easy scoring opportunities, and look to get foul calls (instead of looking to score) when there isn't those opportunities, it's not exactly a recipe for winning basketball in the postseason now is it?
To make matters even worse (and what ties into him looking to get whistles), his meandering temperament doesn't help him out either. Everyone can see just how lazy, inconsistent and unfocused he is on defense, but it's the same on the offensive end. He doesn't just use minimal effort on defense, but he uses minimal effort on offense too. He's constantly looking to take shortcuts on both ends; exhausting the loopholes in the game. It's why he fades in and out of games, and why he can't keep the tempo or provide consistent and efficient offensive production when things get tough (i.e. in a playoff setting).
I mean how can a team expect to win in the postseason when their leader/#1 option takes this sort of approach to the game with these crippling, bad habits?