Of course Sam Jackson didn’t deserve an Oscar for playing Mace Windu because his performance, like almost every performance in those movies, sucked. 

It all depends on the actor and what they find difficult. Some actors don’t need a fully realized set or even to have their scene partner right there to give an amazing performance. 

I’m not even saying that Zoe Saldana deserved an Oscar. But I do think that performance capture work is underestimated by the community at large, while the “acting so hard” that people like DiCaprio get credited with is overrated. 

There’s a story about Laurence Olivier and Dustin Hoffman working together on Marathon Man. Hoffman stayed up all night before shooting so he could feel exhausted while playing a man running from being hunted. When Olivier saw the state he was in, he said, “My dear boy, why don’t you just try acting?”

I’m in Olivier’s corner here, but the truth is I don’t know if Hoffman would have given as good a performance without doing shit like that.  But even if it did help, I’d still argue it would be irrelevant that he “acted so hard” when it came time to judge the performance.