Well if Rudolph is so special when is he the farthest away from Santa?
Why is Rudolph the furthest away?
Well I suspect it has something to do with either a) "leading the sleigh" can't be done from the back and/or a NAV light that's sitting in the back and not lighting the way isn't very useful.
I'm guessing it's based upon dog sleds. The lead dog is the on in front he sets the speed and keeps everyone in line. There's a very special place for every animal depending upon their strenghts and the lead or furthest away is usually the best.