Er...
Let's say you're racing against three other people, and you disconnect at the beginning of the first race. You get three losses, because that's how many people you "lost" to, or were racing against when you disconnected. The other three people, however, are unaffected, other than the fact that there is one less person racing.
Now let's say you're racing 1v1 with someone, and you quit right before the end of the 4th race. You had lost all 3 races beforehand. You get a loss, because you "lost" to the guy you were racing against, but the guy you were racing doesn't get a win because he didn't go to the end screen that say "Congratulations you win!" I know, it's messed up, but that's the way the cookie crumbles, so to speak. Other games work may work differently.