Woulden't it be nice if you could give a thumbs up to players who stick it out and don't quit or concede, or even just if you had a great game with them and they were good sports.
The reason why I bring this up is cause I just had a devistating match with a couple of people who me and my team mate were sure were gonna rage quit. But, they didn't and they tried their hardest even when drowning under the weight of Giants. We wanted to give them a pat on the back and a good show for sticking with it right to the end.
Although it might be obsolete by the time Concedeing matches is implamented, it would be nice to be able to 'up vote' a player for good conduct and sport. (no down-votes, as that'd enable abuse. Only up-votes.)