See thats not what happened here.
This wasn't a cardio machine getting tired this was a calculated assassin deciding to charge at an opponent in total disregard to his own safety.
Everyone always assumes that the effects of PED's are purely physical, strength or Cardio related.
Not saying this is the case with Werdum, but if an athlete has used PED's for many years and then goes without them, it can have a huge effect mentally.
Say for instance youve relied on PED's for cardio, without them you will have lingering doubts about your ability to go five rounds, these sort of things can mess with your head. Weve seen several cases of normally agressive fighters being much cagier with their approach in opening rounds, not sure of their ability to maintain a high pace for too long. Once youre n the fight that can have a big impact, tough first few minutes, " shit, this might go the distance, do i have the cardio without ped's to go that far??" doubt sets in, "shit, no i need to finish this now",... makes mistake.
Same with strength, ability to take a hit, again, coming off ped's, can damage the confidence, do i still have the ability to take damage?
The mental aspects of coming off ped's is huge. If they are something youve come to rely on, short term, after coming off confidence and in turn decision making etc can all take a bit hit.
That may or may not be the case with Werdum, there arent huge physical pointers showing he suddenly looked crazy different, but dont write the possibility off just because you relate PED's to strength or cardio, mental aspect is a big part.