The problem is that that favor doesn't depend on length of the game, only the stats on when it ends, however it ends. Let's say one player on the team buys 5 citadel upgrades, and nobody else does. If that game goes to the bitter end, he's going to get the favor for upgrades. If the losing team forfeit after he bought 3 upgrades, he'd still get the favor for upgrades.
And then the system would also need to be robust enough to discount obviously faked/padded games (1v1, one guy kills another once, the guy killed forfeits and the "winner" racks up favor for winning, most kills, fewest deaths, yadda yadda).
It is a good idea, there just has to be some more control around it to prevent abuse and score padding. Mostly around the out-of-game ladder stats collection.