Rousey was a one trick pony who used the same submission hold for all her wins.
It didn’t take long for opponents to figure out she was one trick and develop a strategy to avoid it.
Which reminds me of what Howard Cosell wrote about Mike Tyson in “What’s Wrong With Sports?” He knew the one boxer who could defeat Tyson — sadly, he died before that boxer beat Tyson twice.
It wasn't nearly that simple.
First of all, when Dana White hired Rousey, he created the UFC's women's division expressly for her. For years he had claimed he wasn't interested in women's MMA because the just couldn't fight. Something about Rousey made him change his mind.
The talent pool at first was very shallow and as she gained popularity, he hired better fighters, more credible opponents, away from the competing promotions. For the better part, the opponents she had at the beginning were anything but the cream of the crop. Once White started investing in the expensive talent, her opposition grew much stronger.
Second, her coach had her start mixing it up more. Initially she only punched in order to get close to set up the arm bar. Beginning with the Alexis Davis fight, she switched to using punching as an offensive tool to its own end.
Rousey knocked Davis out in 16 seconds, the 2nd fastest KO in UFC history to that date, mostly because no one expected her to employ punching in that fashion.
Based on an ultra-quick knockout, her coach kept having her punch with bad intentions. Two fights later, she KO'd Bethe Correia (with punches) in half a minute, which reinforced her coach's belief that she was on the right track.
But her next fight was against Holly Holm, a polished professional with considerable experience (and success) in both professional boxing and professional kickboxing. It was a YUGE mistake for her coach to tell her she could bang with Holm because her two punching KOs were against tomato cans, and Holm was anything but.
Third, in the end, with the talent she had attracted to the UFC it was inevitable she would meet her match soon enough but it wasn't over-reliance on the arm bar that did her in, it was going away from her bread-and-butter and pretending she could bang.
She now claims she was prone to concussions because she'd been hit in the head so many times in her judo career, but it seems a bit suspicious she waited 10 years to point that out.