It is not easy to be a NFL rookie. They have little time for adjusting between college seasons ending and training to become a pro beginning. After the combine, pro days and the draft itself, they have to get ready for off to a new city for mini-camps, workouts and organized team activities before they have chance to wear steelers jersey.
The changes are already too much for them, and they also have to face new scheme and competing against skilled professionals. Position swtch will just make them struggle more. It will make the adjuting period longer, let alone other things such as the stance, weight transfer, hand placement and techniques necessary to get the job done.
League owners really need to consider carefully before they make decision on position changes.