In both examples the fighters have changed their styles significantly to suit the needs of their careers and the types of opponents they have to face. That takes an enormous amount of dedication.
Early on fighters had little to no footwork so you had a lot more opponents that simply stood around or moved poorly. This lead to fighters, in both examples you posted, have enormous success due to their athleticism and maybe somewhat of an edge in technique.
These days just having athleticism and a slight edge isn't enough to win fights. Not for fighters that are far outside of their prime. Overeem had reinvented himself at least four times over his entire career. AA has also completely reinvented himself in probably one of the most complete transformations in the UFC.
There are other examples too. Rose took one loss against Carla and spent the following three years completely reinventing herself. Joanna broke her hands twice in a row and practically fell off a cliff within 5 weight cuts to 115 forcing her to change her style twice.
The success and failure of these changes depends significantly on the coaches, the athlete and the promotion's willingness to entertain a fighter's need to redevelop and allowing them to pick favorable opponents.
TLDR: I can only speak of Joanna's mindset after her losses because it's what I'm most familiar with. She took each loss really hard. Much harder then what people have seen but she kept trying to find the silver lining. Whatever she can cling to for motivation. Even if it seems, at a glance, silly. The others have come back too. Overeem, AA and Rose. They must all have found something to motivate them. Not everybody is a complete sociopath that can just switch that shit off and go back to how things were as if it was just another weekend. Although those people do exist in the UFC.
