Screen presence has nothing to do with size. Just look at Jet Li. It just happens that Li or Staham are also actors, and they do have charismatic screen presence. Seagal has none of it, regardless of how good he is/was at martial arts. The guy who played Darth Maul, Ray Park, has more charisma than Seagal, I'm not sure he's much of an actor though. But this guy means business as well!
Li would kick the ass out of them all. Case closed.