They were both playing Free Safety last year. John had started out as a strong safety but the moved him to FS pretty early in the season. He actually knows both positions and the corner positions as well. Busby got a few reps at FS and was played on 1 Sp T and John started on 4 special teams and didn't see the field in a skill position last year.
Zed IS the fastest back we have with John at a close second. Busby was more seasoned at the start of last fall but moved down the depth chart.
It really is a situation of some of these players being able to remember the plays. Athletically, they are all pretty even for FS across the board. BUT, leadership and field smarts will level out who wins this spot next year. (But, I'm pretty sure Zed will start as FS. Can't see Warner being consistent.) Trice was an exceptionally smart player and made plays because of it. He was also a huge leader. My money is on possible position changes for a few of these athletes and an unclear starter up to the first conference game.