Yes, you are hurting your team. (Destiny)

by dogcow , Hiding from Bob, in the vent core., Monday, August 24, 2015, 21:50 (3476 days ago) @ Kahzgul

Third, because you can't distinguish between poor connections and poor sports, you often get a larger percentage of players who mean well but have bad connections all in the same game, which just means the multiplayer experience for those players is going to suck major balls with people joining and dropping all over the place and they may as well quit because they'll never finish a match and it's because you've only matched them with other unstable connections.

I have trouble swallowing this. Poor connections will DC fairly randomly, win, lose, or draw. Poor sports will not DC if they're winning. Seems pretty simple to me. Now, if your sample size is only one DC, then yes, there is no way to tell, but you can develop a profile over a period of time.