I may very well be called "Captain Obvious" here, but bear with me. Ronda Rousey has one of the greatest armbar techniques in all of combat sports history. Now, although Rousey's armbars are often credited to her being trained since childhood by her mother AnnMaria De Mars, the fact remains that Rousey's "Fight IQ" plays a huge role in the success of her armbars.
In simple terms, Rousey knows exactly how to adapt her armbar according to the direction in which her opponent moves, as well as the leverage that she has over her foe in a given grappling exchange. For instance, in her armbar submission wins over Liz Carmouche and Miesha Tate, she used a relatively traditional armbar technique.
Nevertheless, at UFC 184, her opponent Cat Zingano literally flew into Rousey – throwing a flying knee straight out the gate! Well, Rousey adjusted, and turned the striking exchange into a grappling battle, by tapping out Zingano via a straight armbar.
Rousey's innovation with the armbar is what made her so very successful with the move.