Especially for Rockhold. He's had a longer career and has had his lights absolutely turned off 3 times in the past few years. While Chris has taken damage, he's only been completely leveled once, and that was the Yoel fight.
Rockhold has a successful and more lucrative career ahead of him in modeling, but he needs to capitalise on that now before he gets too old and his face too battered. Weidman just has fighting, and he has less holes in his game.
I must be the only one on this board that can recognize he's had relatively bad luck: in the only 3 fights he's lost, he was winning before getting caught doing something stupid. The spinning heel kick against Rockhold, ducking for a telegraphed shoot and catching a knee against Yoel, and trying to milk a DQ win against Moose. All of those fights could have gone differently if he didn't make one stupid mistake.
He's also fought 4 of the top 5 in his last four fights and just beat the guy now fighting for the belt.