I love Reneau. Her story is amazing; a random PE teacher in her 30's who had never done martial arts of any kind, and was simply in good shape and athletic, having played D1 sports in college.
Had she started martial arts when she was young, we might be talking about her as the greatest female fighter ever.
And I happily played Reneau at +200 against Kunitskaya, which was excellent value, since I think she deserved the decision there. However, she was noticeably worse in that fight and then a LOT worse against Pennington. (Which I didn't bet at all due to that very concern)
Her cardio, once quite decent, is now poor, and her striking is much slower, with worse reactions.
It's not a matter of "training hard", either. Reneau always trains hard and is in phenomenal shape. But at 43, the reactions and endurance aren't there anymore.