Not necessarily. There are plenty of great actors who don't receive an Oscar. Truthfully, I think award shows are stupid anyways and don't have any real merit in terms of measuring someone's actual acting chops.
In Shia's case, I would say that he's a pretty great actor when he wants to be (and these days I think he does, pretty much exclusively, given how much he bashes on all the "plot-oriented" movies he did early on in his career - probably in reference to
Kingdom of the Crystal Skull, the
Transformers movies,
Disturbia,
Eagle Eye, etc.). It really is, just as
@Nurhachi1991 said, a matter of him having gone off the deep end and becoming endlessly controversial since those early films that has caused him to be overlooked by most. He has some legitimate talent and skill. Unfortunately, he has no impulse control in real life and he frequently shoots himself in the foot. He'd receive more accolades if he just quit acting like such a moron. And this far into his career, it's about high time he took his own advice to "just do it," too, so that he can preserve whatever he still has left.
Starting with snatching that fedora back from Kanye West. I don't know why it bothers me so much that Kanye West has it, but it does. Probably because it's Kanye West and he rubs me the wrong way.
Kind of reminds me of the rapper Azealia Banks, actually - she's very good at rapping (lyrical content aside, but then again, what rap actually has good lyrical content?), but she doesn't know when to shut her mouth and act like an adult, and in consequence, her career has been permanently stifled because of her unlikability.
At least she's a better rapper than Kanye West.