Surely it's just driving styles? It's all been said before but Button has been claimed to be a much smoother driver.
Jenson was branded with "smooth" style primarily when he was with Brawn. Many forget that he had an advantage...the double diffuser. It made driving the car so much easier than all of the other cars that year...all of which had far less rear down force. You can see the difference since he's been with McLaren...when the car is very good, smooth gets him nowhere. When the car is so-so, he has no grip. When the car is bad, he has no grip. Lets venture over to the other side of the garage, shall we? When the car is good, Lewis is on pole and/or wins. When the car is so-so, Lewis is either on pole and/or wins or is on the podium. When the car is bad, Lewis still ends up being very competitive, fighting at the front.
As far as the Hungarian GP, from my armchair, I suspect McLaren called him in early because of his fading early pace and his history of losing tire life very early in races. They likely believed they could do three short stints as long as he can be blindingly quick and make it work. We know he isn't blinding quick so that was fraught from the very start. Part of his issue this year is McLaren rate him higher than he really is and the results show he can't live up to their assessment of him. They put him on these strategies that he can't cope with and then he looks bad. Tough place to be.
I'm just saying...