I think Steve Vai could easily beat up John Petrucci. For starters, he is much taller and with a longer reach. He has very big hands and can make a big pummeling fist. He wears those cowboy boots with the pointy toes that would really hurt if he caught the hapless DT guitarist between the nuts.
Conversely, John Petrucci is kind of small and effeminate and doesn't look very strong. Even though he now has a beard, he doesn't look any more manly or menacing and you know that most teenagers would have no trouble taking him in a fight. He looks like the kind of person whose parents made him take ballet lessons and he secretly enjoyed them. On top of this, he wears this footwear with rounded toes like and orthopaedic shoe; not much use in a scrap.
Vai 1 : Petrucci 0