Well we all know boxers are not used to kicks, and have no ground game, but assuming they just brush up on that a little bit I think they can (but not necessarily will) beat Chuck or Sylvia. The thing with boxers is if they get inside and start swinging, try and get too close for the kicks, they can kick some ass. The hand speed, power, and combinations from a top notch boxer can end a fight real quick. With Chucks wide style, I think if he gets caught, the boxer will be able to capitalize and fallow it up with a combination. If a good boxer can go on the offensive with guys like Chuck or Tim, I think they have a pretty good chance of winning.
"Everybody underestimates the kick in the groin." - Bas Rutten