One of the trends that has developed over the course of the past decade in the NFL has been for players, particularly young ones, to seek outside coaching assistance, hiring position trainers during the offseason to work on their craft with them.
This practice has, in fact, become pretty much ubiquitous at this point. Not only has the increase in rookie salaries helped contribute to this, but so has the dearth of contact that teams can have with their players during the offseason, so if they do want to work on something, they have to seek help on their own.