Impressive young talents like McKenzie are often overused early because they are so special and can provide a spark to a team struggling to make points.  Denver is capable of falling into this trap like they did in Buffalo.  I like the go slow approach with keeping this talent limited to special teams for now.  Rick Upchurch comes to mind in this repsect. McKenzie needs to develope consistancy.  His ball control skills look a little scary when he is on a tear. Turnovers are killers and the Broncos are prone and have plenty to deal with on pass protection and getting their receivers open. Keep McKenzie where he is until he and this offense gets more established.