Implementation of Fifa like online ranking system would take care of the quitters. Besides no one would care about their opponents quitting as long as one gets win and the record gets updated. For instance when someone quits against you in fifa, when the score is equal or you're leading by a goal or two, you get win by 3-0, even if the score is like 2-1, when your opponent quits, you get 3-0 win. In case you are leading by 3+ goals, you get to have the same amount of goals that you've scored and the score of your opponent gets cut down to 0.
Now for example if you're winning a match by 5 wickets or so with ease and your opponent quits, winner should be provided with bonus, like instead of 5 wickets, it should count as with 8 wickets or so for earning additional XP, higher the winning margin, better the XP. Although all of this would depend on the rating system which you guys implement in the game.
One other simple solution would be to restrict the online access to one account per serial key so that no one can change their account or hope for starting over with a better record. Quitting would increase the DNF (did not finish) percentage so no one would quit... High DNF% = less likelihood of finding an opponent... We all know that everyone hates facing quitters.