My cat is a perfect example of that. Cats are purpose built to be the ultimate killing machines, but my cat has no idea how to hunt.
She tried to chase after a spider this morning, but spent more time dancing around it than actually swiping at it. Plus, she constantly lost track of the thing and would start to wander off.

She's not the smartest cat on the block by any means, but the reason she's a terrible hunter is because she never learned how to do it properly.
If I didn't feed her every day, she'd be toast.