Dana and the UFC is partly to blame for this. TBH I never really saw a ton of skill with her. She would just aggressively charge the women in the UFC...she was bigger than all of them.
When she did face competition that had skill she got knocked the fukk out. She got exposed, tried to come back and got beat on again by good competition. The WWE was a wise career move for her long term because many in the general public can still buy her as some sort of legendary Female MMA fighter, when in reality if she had 4-5 more "championship" level fights in the UFC that might be another 4-5 L's.