if Chavez jr. has a chin like his dad, he could conceivably outlast McClellan and win. That remains to be seen, because Chavez hasn't fought anyone remotely dangerous. Until I see some evidence (such as maybe laughing off the wildest, cleanest haymakers Monkey Martinez can throw and walking him down) that Chavez has an abnormally awesome chin, I would have to venture that a big hitter like McClellan would knock out a relatively ponderous guy with sub-par defense.
Chavez jr is clearly the more active guy and thus captures a workman-like decision, surviving a couple of scares on the way
