Mine go as follows:
Braxton Miller for improved leadership and showing the initiative to go to San Diego and improve his game when he easily could have been sitting around taking a break.
Jack Mewhort because he is the best player on, and leader of the offensive line
Bradley Roby because he is the best defensive player (say for Shazier?), and is showing leadership in teaching the young guys the way to do things.
Ryan Shazier for being a leader at LB and also being the back bone of the LB corps.
lastly I have a tie, so I could go with either guy, CJ Barnett/Christian Bryant because of the talk of both being vocal leaders during practice and being players the young guys look up too.