I do not know this is the reason 100% but it seems based on my research this is the cause. I won 10 in a row and the achievement did not pop, the same with a friend of mine. On my 13th win in a row the achievement popped. During my 13 fights 3 people quit as I was doing my fatality. The same results from my friend but only twice. It seems that it's not counting it as a win, even though it does for the leaderboards.
I wonder if this has the same effect on your 100 matches or not. It's a shame that people are such bitches that they would leave when you have won. It does not stop their loss so they are just being complete dicks. I cussed one guy out and he said I did it because you did the same move over and over. With the lag in this game I can not help but to do smokes disappear special on accident and it has in fact cost me more matches then it has won. When I fight a guy and I know a leg sweep will stop his up high block I try to sweep and find myself flying in the air, the oppontent blocking it and countering with an uppercut :(