Rey Mysterio beating Big Show is just stupid no matter how you put it. The height difference is just too big. I don't get why they do that, but they haven't done it too much, but Punk could definitely believably beat Kane.
But, I didn't mean Punk should win every match clean, but just after a major program, throw in a guy that Punk can beat clean, lke Miz or Kofi in between programs where he goes back and forth with a guy.
That way the heel would still have a legitimate claim to say that he is the best in the world.