I don't know, when I hear dominant, I think players who are so impossibly good that they force other teams or players to completely change the way they play, or just can't be beat normally.
It's hard to think of quarterbacks as dominant because they're not going one-on-one with other players, and none of them are going to be head and shoulders above others. As such, I'd leave all quarterbacks off this list.
In my mind, Gronk is probably the most dominant football player of the last 20 years. The only way to defend him is to interfere with him or hold him. Similarly, I'd name Shaq as the most dominant (but not "best") basketball player of the modern era for that reason. Tiger was just heads and shoulders above his position and augured in an era of athletic golfers. Phelps was an impossibly good swimmer.
It's hard to argue with a lot of the people on the list. I'd probably put Serena higher. The one thing I'll say is it's weird to have multiple players from the same sport whose primes overlapped as dominant. So either Messi or Ronaldo; Djokovic or Federer. Not both.
Curious absence of hockey players on the list, too. Surely one of Dominik Hasek, Nicklas Lidstrom, Alexander Ovechkin, or Sidney Crosby belonged.
