First things first - I think
he is washed and he should retire. But I think it's more than just being old and shopworn. He had bad match-ups after bad match ups
and vs. top flight competition. But his last fight shows something more -
his style is kinda outdated in modern MMA.
So... why?
He's not a fleet of foot point fighter or in your face dutch stylist, his thing is
striking geared against wrestling shots complimented with decent jitz off his back, if he gets taken down. Nowadays the base level of MMA striking (specially at 155!) is a lot better than even 5 years, let alone when Cowboy was in his prime. The wrestlers he chew up before, now can do it all. Maybe two-three years ago I would've said his style is outdated at the elite level, but the game has gone so far that now his style is outdated a level below that.
He is totally fucking up short and stocky wrestlers/grapplers who have loopy hands and stay at kicking distance with him (Iaquinta, Hernandez).
But he gets flummoxed by rangier guys, or even people who throw just more of a straight shots (and feints) and are not crashing the distance predictably. His posture is too upright, upper body too stiff, feet stuck in the mud... He can't compete in boxing range, can't chase down mobile strikers and equally can't get away if he's pressured.
Dedicated strikers fuck him up badly (Till, Masvidal), but even just more composed fighters who can pressure him relatively safely and are taking the iniciative just outpoints him. Examples are Ferg and the the dollar store Ferguson - Niko Price.
I'm sure some of you who are a lot better with the technique terms and have watched a lot more tape and maybe have practice can add more detail (which I would love to read), but in short this is my take -
Cerrone mainly ran out of comfortable match-ups. There is hardly any Patrick Cotes or Rick Storys at WW anymore, and at LW are even less - you gotta look for guys outside the top 20...
Cheers!