How Does Loss Prevention Work for Ranked?

Can anyone explain how loss prevention is activated or works? I just got out of a ranked game where my team had two dc'ed players for the first 10 minutes of the game, and then one additional dc towards the middle of the game. You would think there would be a system in play to detect that, and the IP loss wouldn't be significant, or someone in there promos wouldn't get screwed over by a loss stained in their series, right? I figure there has to be something in place where players who experience losing games to dc's would be protected from the negative impacts that come from losing. I have a replay of the game I just came out of. it would just seem a little bit unfair to players who have to suffer through a 2v5 or 3v5 for a majority of the game , and still come out losing everything that they just climbed for. So how exactly is loss prevented activated?