525 cs and I get an S- (close out the game when you're ahead)

http://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/2391974475/202439140?tab=overview

Pretty uneventful game....until around the 40 min mark, then it went off the rails. I thought we were gonna lose after they took all three inhibs, but I guess my team wasn't having any of it. If anyone on my team is reading this, thanks for the carry, you're awesome.