I wouldn't say they are overrated.
The reason is the number of major victories each fighter collected in their career. Also loses don't always look the same. In some cases a loss that came in a competitive fight may be more impressive than a win.
Also note that many fighters go through losing streaks in mma. I don't think it is as easy in mma to accrue a big record than boxing if a fighter ever jumps to a major organization.
Perhaps Randy didn't always deserve the fights he got, but he won enough big fights that I would say he is one of the greatest HW's of all time. Don't get me wrong, I agree the ability to stay in a winning way matters in a fighters legacy. However, I also think being able to bounce back and win a big fight when you are the underdog can factor in too.
I think BJ may also be the greatest LW of all time period.
Otherwise you would probably go with Takanori Gomi who had the most impressive win streak of any title fighter in a major organization to date.
However, notice .... BJ beat Takanori Gomi when both fighters were "in their primes".
Some fighters are constantly given big fights, and so they don't pick up the rebuilding victories that others do.
BJ is possibly my favorite, or the fighter I most respected of all time. He had such amazing skills. I don't know if he is still in the GOAT category after losing those fights to Edgar, when you have the amazing runs of Anderson, Fedor, GSP, and JBJ.
However, BJ is as good of a pure mixed martial artist as any fighter who has ever competed in the sport!
