The way I understand it, 'pre-match' isn't like 'early decision' from your high school days. The gist of what I've been told is that cruddier programs will jump at the opportunity to offer a pre-match to a student they like in order to lock them in.
It makes perfect sense. If there's a program out there that is desirable, what do they care whether they get you or some other ravishingly handsome, erudite double 99 with two years in the Peace Corps? Such a program will be confident that they can get grads who have great stats and really want to be there.
So the answer to the OP is essentially that you have asked an irrelevant question. You could barely pass the Step and still be offered a pre-match if a program has trouble filling their slots every year...... or you could get a 250 and not get any pre-match love from sexy programs.