Guys who were pushed too fast, and fizzled out?

Okay, but I think you're possibly confusing guys who just didn't perform, compared to guys like Vargas who were just pushed waaay too fast.

Meldick Taylor - JCC definitely did ruin that guy, he pummeled him. However, at the time the fight was made, I think Meldrick had definitely proven enough. This was just a case of a guy taking such a beating, that it completely derailed his career, not so much of him being pushed too hard IMO

Michael Moorer - had already been a champ before he fought Foreman. He was never a tremendous HW to begin with though, I'm not sure it was really a case of being pushed too fast.

Riddick Bowe - Was well established when he fought Holyfield, was the best contender available at the time for Holyfield with Tyson being locked up. Those three fights did cost him a ton, but the Golota fights are what really ruined him. He never has talked the same since those encounters...

You definitely named guys who had fights that had a very detrimental impact on their careers, I'm not sure those choices fit the bill for being "pushed too fast" however. Some may disagree, we'll just have to see :goodGood ideas regardless though bro.