My son, becoming more interested in the Star Wars movies, purchased with his 'Tooth Fairy' money the third episode in the series ("Revenge of the Sith"). I stayed up late to watch it so at least I would have possible explanations for all of the questions that I get asked about the characters in the Star Wars universe.
That and it wasn't that bad.
Anyway, I noted that Natalie Portman's performance wasn't stellar, and she I know has a track record of good acting, and so I conclude that
the directors/producers are in some part (major?) responsible for the actor's on-screen performance. We can't blame it all on Elijah, Sean or John.