She was, much more than Kaido was. Pretty much every time she was against the Straw Hats or their allies she was handicaped, dumbed down, nerfed and clowned. Instead of treating her as a Yonko and top tier Oda made a circus of her performances in battle save for a very few moments against people who aren't Straw Hats or allies. Of all the shit writing and fighting Oda has ever written, the way he handled Big Mom is on a whole superior class of its own.
The perfect example of what to not do and how to not treat antagonists, fighters and characters in general.