In fact, I think each and every one of the actors have done the very best they could with the material provided them, even when considering how little screen time Anton Yelchin was given in Star Trek (2009) and Star Trek Into Darkness (2013). Sadly, Star Trek Beyond (upcoming) largely looks like it's going continue into Trekdom's thematic decline, the latest gaffe being actor Chris Pine's admission (paraphrased) that "Star Trek can't be cerebral any more."
All griping aside, I -- probably like most -- was absolutely gobsmacked with the news today that Yelchin was the victim of a freak accident (apparently by his own hand and with his own automobile), leaving the young actor to be found dead by friends and family at his own home this morning. It's sad, sad news to have to share; he was a young talent with plenty of promise. Thoughts and prayers go out worldwide to all those in mourning.