Matchmaking on Dominion is in its own category of stupidity. Me too will go on winning spree (not stomping, just fair, sometimes pretty tight wins), but then the engine decides to put me with completely retarded players just so that I can have same number of loses as I had wins previously and to keep my win-lose ratio on 50%. By completely retarded I mean morons playing Anivia putting the wall in front of teammates right at the moment of initial going out from base, afkers that say mom called them to lunch or that they need to go smoke, players that play Dom first time (I have around 400 games and the engine puts me in a team of players with 10 wins, wtf?)...
I could go on and on, but the point is, matchmaking system is totally rough and stupid.