I didn't interpret it as you comparing Westbrook's potential to Huestis' (and I don't think campbest was either), but even if you're just comparing specific skills, it still goes back to the issue of comparing players at different ages.
Westbrook converted college 3s at a higher clip (35.4%) in his first two seasons at UCLA (at ages 18 and 19) than Huestis did his last two seasons at Stanford (33.8%, at ages 21 and 22).
At age 22: Westbrook hit 33.0% of his NBA 3s; Huestis hit 33.8% of his college 3s.
Westbrook isn't a terrible shooter now: his percentages are deflated by volume and sometimes questionable shot selection. However, if I'm drafting a wing with the hope of turning him into a 3-and-D guy, I'm not thinking, "I hope he learns to shoot it as well as Westbrook." I suppose he could learn to nail elbow jumpers like Westbrook--which might be useful if he were a 6'10" pick-and-pop big like Serge Ibaka--but that's not exactly the type of spacing you're hoping for from a wing.