Hum. I think that playoff match is bogus, I've never heard of anyone playing it. So, either you both won (unlikely) or they used some other tie breaker, between your record against each other possibly?
Head to head is 6-3 in his favour, one win each. He isn't in any of my league or cup draws either so no way of finding him. Only other criteria I can think of is team value as mine is lower, seems an odd way to decide a league title though?!