I would tend to agree, but Wisconsin has the same problem of not being able to hold on to blue chip prospects and seems to be able to maintain success. Wojo coaching at Marquette has been a big thorn in Wisconsin's side as he has more of an appeal to blue chippers as he comes from the Duke/Coach K tree. Both the Hauser brothers went to Marquette, Diamond Stone to Maryland, JP Tokoto to UNC, Tyler Herro to Kentucky, Jordan McCabe to WV, etc. Really the only in-state blue chipper that Wisconsin has held on to recently is Sam Dekker. I will concede that Wisconsin does have a larger recruiting pool with Chicago being nearby, especially finding that diamond-in-the-rough like Frank Kaminksy that everyone else passes over.
And maybe this is where coaching comes in a little as well, and the ability to coach up a 3-star like Ethan Happ who only had 3 total offers, the other two from mid-majors, and allowing their system to help make him into an All-American.