Here's a homework assignment for anyone who doesn't feel that these guys should be suspected of PEDs.

Go on a bodybuilding forum and tell them you want to put on 15lbs of muscle, but you're not interested in using steroids or anything like that. You'll get a wealth of suggestions and tips.

Among those tips, you will NOT find "run X miles a day". You won't find "start jumping rope" or "start doing wind sprints".

Why? Because endurance training (which is a LARGE part of what boxing trailing entails) is not conducive to bulking up. It is totally counter-productive. When a bodybuilder is bulking up, he eats a ton, he lifts heavy weights for low reps, and he makes sure to get lots of rest and sleep. He doesn't do a ton of roadwork and endurance-building activity.

So when you see a guy, out of the blue, suddenly bulk up 10, 15, 20lbs while maintaining the incredible aerobic training schedule that a boxing camp entails, that's suspect. I'm not saying it's impossible, but it's not normal.