I would think, similiar to most Spring & Summer drills, that every 2nd string player challenges for the 1st string position...(Although I am not sure Calvin Johnson ever feared losing his starting spot...although I hear he's got a heck'va work ethic..anyway)....it's all part of the competition. I am confident that with the recent coaching changing that it is and will be made known....Earn your spot by working hard & displaying your knowledge and execution of plays....a lot of which will be NEW PLAYS so....lots of work/learning to take place on the coaches & players parts......All that said to say....Earn it or lose it to someone else that wants it more....I am sure CPJ & his staff have made it known.