After rewatching some of the game, i'd say there really isn't a true 5 on BYU's O or D for a lot of the game, but there are a lot of times like in the time stamp above where BYU is in their set Defense and KC starts out being the only guy playing low in the key, and many times he is the guy defending florida's bigs in the post instead of Hartsock. Maybe it would have been more accurate to say we played KC in the post on defense and he defended Florida's bigs when they had the ball in the post as often or more than Hartsock.
Late in the 2nd and in OT Both Hartsock and KC played more like Forwards and neither one really played a center type role.