Yeah, the thing with Kapler is that he was all talent. Consistency, proficiency, competence in the sport he devoted his life to, these were things he never really got around to. He had talent galore, and made his bread by flashing it far too infrequently. He looked good when he was on, but to call him a good ballplayer... well that's a real stretch. He was a physical specimen who never really figured out that whole "baseball" thing, and never, ever lived up to his talent.
Nava is pretty much the anti-Kapler. Much less raw physical talent, but he can do a great deal more with what he does have. And it's not like all that Kapler talent really allowed him to make anything of himself, so it's kind of a trade-off.