I am going to speak from my own personal experience. In the early '80s I was working on an ENGINEERING degree in my junior year. My work study assignments varied, but one semester I got to be the assistant track manager (bottom of the totem pole for sure). I had to be there at noon BEFORE the atheletes and left a 5PM, which was AFTER the athletes left. So I had to schedule my classes in the morning. I made my best grades ever that semester carrying a 16-18hrs of school work on UPPER level ENGINEERING courses. It can be done. There are some students that work longers hours than I did working odd jobs. So, I don't buy it. They have enough time for school.
This is a prime example of how one has to manage his/her time in order to be involved in college athletics and still make academic progress. With that said, though, I think most people, especially Sherman and Bennett are glossing over a common practice of most college football players: creative scheduling.
When I was in college, the football players I knew took the classes for their major or any other difficult-to-schedule classes during the spring and summer semesters, when workouts and meetings (other than spring drills) were at a minimum. During the fall semester, they only took the bare minimum hours needed to stay eligible, and they filled their schedules with a mixture of lower level electives, online courses, and independent study opportunities. That method made it much easier to fulfill their football requirements while making minimum academic progress, and let's be honest, the athletic department was always able to negotiate these opportunities for the players with the academic departments.
Again, I'm not saying it's easy, but I certainly don't think it's the drudgery that Sherman and Bennett made it out to be, especially when you figure that many of these guys are working toward degrees in underwater basket-weaving, recreation administration, or human reproductive sciences.