He certainly deserved it for leaving Las Vegas, a most moving performance, so nuanced and heartbreaking.
I am actually surprised he hasn't been nominated for more of his roles, he's had a lot of really great parts. Bad Lieutenant stands out for me, and Matchstick Men too.
And if we are not being Oscar centric about it, I admit perhaps I am a tad more partial to those awards voted for by the public, Nic has received a huge number of awards for his roles across the three ddecades of his career!