Base player development

Is the base development ability for the players in this game automatic regression? Because even with the training camp and the default schedules being 5/5/5/5 or some such as to where the players are not fatigued, it seems like they just automatically regress outside of a few people who are playing near every snap.
Does work ethic of the individual player count for that much, because at least for my franchises I try to recruit high WE players and they still regress, but if I crank up the schedules then they all get super fatigued.
Does work ethic of the individual player count for that much, because at least for my franchises I try to recruit high WE players and they still regress, but if I crank up the schedules then they all get super fatigued.