It's happened many times. You are down 2-0 and the other team gets a red card so you go all out to try and come back but the other team catches you on the counter-attack and wins 3-0. No, I can't give you a specific example as I'm not a football encyclopedia but it happens and it makes sense. I have seen about 15-20 games with red cards in them and almost all of them ended bad for the team with a red card but exceptions happen.