Kind of reminds me of what people used to say about Tim Tebow in the NFL...he is a great "football player" but not quite meant to be a QB. Well, with all due respect to both Tebow and McCaffrey, as great as athletes as they are, they don't honestly fit all that well in any other position, either. Perhaps a slash role and spot duty is the best we (or whoever he ends up with) can hope for. A player can make some great contributions in such a role, and there is no shame in that.
But if the aspiration is to be an NFL QB or bust, that may not be in the cards.