Top cringe whenever anyone says Cain "took years off his life" and "ruined him". Junior took Stipe's best shots for three rounds, and looked light on his feet, a year after the second Cain beating.
Junior's massive decline "coincided" perfectly with USADA. Aggression was completely gone vs Overeem, which was his first fight post-USADA. Chin also left the building for that fight(traps, neck musculature greatly diminished).
Also "he was never that good" is equally retarded. Speed, power & cardio are essential to "being good" in MMA. PERFORMANCE ENHANCING drugs have a tendency to greatly increase these parameters. Junior is the same man, but with his lean mass:bodyfat ratio getting fucked by USADA, his body no longer allows him to fight with the same ferocity, speed or durability. He's not physically able to string together high power, high speed combinations for more than a short flurry. Also, you think he suddenly forgot how to throw an overhand overnight? No, he's just missing these days because his punches are slower.
Also, when you're really powerful and physically outmatching your opponent, even glancing blows or half-blocked strikes can knock down the opponent, especially at heavyweight. Physicality is a top parameter for success in MMA, and at heavyweight that effect is magnified. It's impossible to list just how many ways performance enhancing drugs are a gamechanger for the thick boys.
Look at the change in muscle:fat distribution.