Chelsea are due to play Arsenal in a soccer match. Mr A prays for Chelsea to win, while Mr B prays for Arsenal to win. Chelsea won the match. Why were Mr A's prayers answered but not Mr B's?
Why assume that Mr A's prayer's were answered? Is the idea of the example that Chelsea won because Mr.A prated for it to happen and God acted accordingly? Suppose I ray for a natural disaster and one happens. Would we assume that this was God answering my prayers? Surely not on any conception of God that's worth taking seriously. That Mr A prayed for what happened doesn't mean it happened because Mr A prayed for it, and in this case, that seems to be the response the believer should make. There's no reason even for a believer to think that Chelsea's victory was a matter of God favoring Mr A over Mr B. Of course, non-believers have an even simpler reply. But I'm treating your question hypothetically.