The benefit of the support runners wasn't just to help him keep pace (he could probably do this with music). They also provide a drafting help to limit any head-on air resistance.
It's supposed to be good for about 2% at marathon pace. I'm not quite sure how long pace makers last in a traditional marathon, but I assume at least half way. So the rotating pace makers today explain maybe 1:12 of the two minute difference to his traditional best time.
