Bradley Cooper might be overrated as an actor but if he is,it's only because there is something about him that relates to the audience and touches all. He isn't the best actor. But he aces his roles because he has what it takes...good energy to relate to people during his performances. You get the feeling he is down to earth.
In Bradley Cooper's role in "A Star is Born", he was very good but nothing that any other actor could not have pulled off. Still, the audience loved him, even when he sang with Lady Gaga which isn't his cup of tea to do. He is personable and not arrogant so those things are definitely in his favor. Is he overrated? Yes, probably. But he's one we love to see so...who cares? Right?