If you are just looking at PG, you will also see some players that are walk-ons not preferred walk-ons. They never sign a NLI and they are not guaranteed anything from the staff of the school. They will go through the walk-on process which each school is required to have. PG does not make the school say if a player is actually committed. The player can put it on his profile. This is not a lot but it is a few each year on most teams. I think you also have to look at how long the coaching staff has been there. New coaches will typically weed out the players they did not sign or bring in with their players so the numbers will be very high the first couple of years of a new coaching staff.