these were all men who were at one time as the most dominate fighter of all time and seemed unbeatable. If you look at their highlight reals on youtube you would wonder how they ever lost (especially the shamrocks).
I see someone has been drinking the kool aid.
None of those fighters were ever seen as unbeatable at any point of their careers. Ill give you maybe the thought that Chuck and Matt Hughes were but that had a lot to do with the fact that they were fed guys who matched up very well with them at the time. Call it a case of a promoter who knew how to make his top fighters look very good.
Fedor on the other hand was a nobody who was basically thrown into the fray to build up Semmy Schilts, Heath Herring and then Big Nog's name, but ended up crushing all of them. No one sees him as unbeatable and obviously as he gets older he will lose his edge like everyone else. That said I really dont see a mix martial artist ever being as dominant or holding a record like he has had in the future.
Oh and the Shamrocks unbeatable? You need to study up on your tapes, even mentioning them in that category, EVEN in a fan boy sense at the height of their careers is amazingly ignorant.