How could anyone think that in 50 years, professional athletes could be many pounds heavier, yet be much faster and jump higher? Oh, that's right, better training and diet! Sure, sure. Oh, and they discovered that using huge rubber bands and emulating the Ministry of Funny Walks in training made athletes much stronger and faster!
Guys, most of the athletes you watch at the college level are taking something. It's rife in high school athletics, for crying out loud. It's openly discussed. Okay, when you see a 215 pound guy show up after the offseason with 15/20 pounds of muscle, that ain't happening "naturally." That doesn't happen naturally because there is no muscle memory there. They were never 235 pounds of sliced muscle before. Bodybuilders who slide in the offseason and then go back on a cycle can do that because they been that huge before.