I think Fred Van Vleet was an ESPN 100 recruit, but Ron Baker (who started the other night for the Knicks) was a kid from a small town in Kansas who was initially a walk-on. He was considering playing for Division 2 Fort Hays State before deciding to walk on at WSU.
It's kind of unknowable, I guess, but I'd argue that he made such a huge leap as a direct result of very high quality coaching in college.