As a Senior in high school, one of my good friends was cast as The White Rabbit in a production of “Alice in Wonderland”. He was really, REALLY, awful. Pretty much ruined the whole play for me actually. Painful to watch, and akward to be around him afterward as I really didn’t want him asking what I thought of the performance. (afraid I would prove to be just as bad an actor when I told him how well he did!)
So I totally get that good actors make it look easy and natural.