As person who actually graduated from college, was a former collegiate student-athlete (on scholarship), youth coach, former academic program director (not athletics, academic degree granting division of major university) and parent, I've known/worked with a lot of students in Nolen's position.
Most of these students had far less time demands (like travel, practices, games, public relations) and public scrutiny (word of the day) than a Gopher basketball player. Most academic issues, not carefully monitored, usually show up between the sophomore and junior year.
I heard that the head of the athletic academic advising office left that position about a year ago and it was vacant until recently. Tubby would have known this and that should have been a big red flag for him and his staff to place closer scrutiny on his student-athletes, especially those with previous academic challenges. I also heard that Nolen (and Williams) were/are not the only players in academic peril.
Any seasoned, experienced coach who really cared about the academic health of his players, would have requested additional University advising support at that time and/or implemented an additional support system. Keep in mind, this key academic program director left sometime between basketball seasons. If Nolen was in academic peril (which he had to have been to become ineligible), it was just as much Tubby's responsibility as it was Nolen's to make sure he got all the support he needed to get academically back on track.
BTW akoch, these services are available to ALL University students either through their academic division office and various academic student affairs offices.