You got to admit the first transformers movie he did, was pretty good. Or do you think he has never done a good movie and the studios that keep wanting him to direct are morons.
The studios don't care whether he makes good movies, they care whether he makes money. Making money is at least as related to the marketing campaign as to the quality of the movie. Bay makes high-concept movies that are easy to sell.
I've actually never seen a Michael Bay-directed movie. I'm happy keeping it that way.