I'm afraid that I respectfully disagree with the Westbrook comparison. Because I grew up originally in Oklahoma (and was excited when I heard that Oklahoma was getting a NBA team), I followed Westbrook quite closely early on. In college, he was basically an unbelievably strong and athletic, super competitive guy with few skills, just about as raw as you could get. And, as you point out, he wasn't particularly productive in college. Heck, he didn't even start his Freshman year and only started his Sophomore year because the starter Darren Collison was injured. In summary, he was super athletic and competitive, but not particularly skilled and very much a work in progress.
In contrast, Fultz has good skills and compared to Westbrook in college is much more of a finished product. I think an absolutely best case scenario for him might be James Harden, not Westbrook. However, that is just my humble opinion.