PVP - losses

How is it, that in the last 20 minutes of a PVP event I lose about 200 in score - but when I look at the guy in 1st place, with NO SHIELD he doesn't lose a single point. I checked out his roster too and it's nothing special, maybe one 3-star hero above lvl 100. It's virtually impossible to get your score up, for every battle I win - I lose 50. Even if I were to be winning matches that give me +40 points I would still be taking a step back. So dumb... There's got to be a better way to go about this, perhaps only allowing a player to be attacked once every 10 minutes?