My only guess with Cal Poly/UC Davis (less certain about Michigan or Wisconsin) is that the many other extremely successful CS applicants from good Bay Area schools also applied there as their 'safeties' since they're in-state, and those schools had artificially high denials as a result? wild guess. I'd suspect there's some "I'm sure you're not going to go here"-denials coming from lower-ranked schools when they get applications from strong candidates. Given that he was accepted to UT and UM and he declined to attend either (I'm making the possibly wrong assumption that his family could've afforded the out-of-state tuition, but given his father's job I don't think that's an unreasonable assumption), I doubt he would've attended those "safeties" even given the opportunity.