I don't think that is it at all. SF and the staff have a culture and program that they are trying to build. Some guys will buy-in 100% and be confident that they are in the right place. Some guys may not feel comfortable and decide to look elsewhere. It is better that they do that and open up a scholarship, honestly. Another possibility is that they really want to play, but find themselves buried in the depth chart and decide that they want to test the water somewhere else. Frankly, that might be best for everyone involved. Roster turnover is commonplace in college football.
These are 18-22 year-olds in a program that had a major upheaval. Stands to reason some guys would move on.
Whether we like it or not, this was always going to be a major rebuild. That gets a little bit easier if guys that don't want to be there move on.