Sure these guys juice - I'm sure Bonds is not as juiced as say Sosa.
But if you watch a little golf (or go to the driving range yourself), you'll soon learn that mechanics and contact can help anyone hit the ball a long way. Tiger Woods is 6'2" 180 and has a significantly faster clubhead speed than anyone on the tour. Meanwhile John Daly just hit a 375-yard drive, and he's just a fat out of shape (220 lbs, formerly 260) slob who really knows how to swing a golf club.
Strength is a prerequisite for consistent power numbers in baseball, but it's also very much a question of mechanics and simply hitting the ball with the fat part of the bat at the right time, dead center.
Pitching is also a bit like that. Randy Johnson and Roger Clemens use two totally different bodies to throw 98 mph fastballs.
Say didn't Babe Ruth juice?????