Not so fast.
I'll agree that CC is faster than Nava, a better defender, and he can hit for more power.
But you can give or take that with Nava's ability to put up sterling at bat after sterling at bat -- an ability that if CC actually had, he'd be the superstar everyone mistakes him for. An ability that we know this franchise, and many other, consider the single most important.
Nava's a little lucky. But if you normalize the BABIP to .335 or so (his career rate in the minors) he's still hitting over .300 and the OBP is still over .400. CC can hit .300, but his OBP has never been over about .360 or so. And with the kind of power lineup we like to field, I take Nava's OBP over Crawford's speed, and suspect that if we had to choose between one or the other to lead off for a full year, with the power we can line up behind each, it would be Nava who scored more runs, as Crawford would be on base less and run himself into an out or two.
In the end, the tiebreaker is probably Crawford's defense. But it's by no means as cut and dried as you're trying to make it out to be.
This isn't just about Nava's numbers. His approach and swing are turning as many heads as the stat sheet. If anything we're seeing from Daniel Nava this year is legit, he's going to have a run of 2-3 years as a starting player somewhere in the majors.