TIto Ortiz ducked Chuck, but I wasn't paying attention to that rivalry.
Anderson Silva being very picky about who he fights, he didn't want to fight Weidman. He said Weidman needed more seasoning. He wanted Rich Franklin 3 or Cung Le.
I also think pulling Stephan Bonnar out of retirement(when tons of dangerous fights at LHW....Texiera, Machida, Phil Davis, Jones etc) showed where they thought his abilities were.
He was willing to fight big guys like Griffin & Bonnar, but not the dangerous ones. That was Silva's last actual victory in MMA.
Ronda Rousey. She couldn't last weeks without verbally attacking Cyborg, but for whatever reasons she refused to fight her. She could beat Mayweather, most male BW"S & Cain on the right night though