Instead of a concede button or people going AFK in sPvP, I would like to suggest an option that encourages players to fight harder and not give up, afk, etc. even against unbeatable odds.
My idea would be to upgrade the current rating system to deduct fewer rating points if you loose within a certain threshold of your enemy. For example:
You loose 495 - 500 and your rating drops 14 - 20 points
You loose 100 - 500 and your rating drops 14 - 20 points
There is no difference so no motivation to not give up, or at least finish with the best possible score you can make.
1 If you loose within 50 points of enemy 0 rating points deducted.
2 If you loose within 100 points max 4 rating points are deducted.
3 If you loose within 150 points max 8 rating points deducted.
Anything lower than that old rating system points apply so you loose 14-20 rating points.
The amounts of points for a win remains the same
I think this will keep players motivated to keep fighting to mitigate the amount of rating points they loose even in an in-winable situation, rather than just give up from the start.