In my opinion the problem of dominion is that there are a lot of players that become afk, disconnected. When Dominion started i think this problem that has made classic bad games would finish, because we were now talking about 20 minutes of game instead of 30~50...
But what i've been seeing is that almost every game we have at least 1 afk, that easily makes his team lose the game.
I have got many wins in dominion, more than 100 games, and i honestly have had more and more bad players and afk/leaving players in my team instead of in the other team.
Just to finish my point, I agree that this way of random player isn't so fair with good players, just because if 1 or 2 good players get a 4vs5 it is almost impossible to win, even if the other team sucks...
So, the first thing LoL has to do is to think in a way that leavers/afk have to get punishments, or not being able to play anymore with good players (i mean not leaving/afk players). If you put your money into the game or not, the fact is that the game is getting worse and worse because of these players that don't leave us alone to play a good game.