Anyone knows how the points you get in PVP are calculated?

My sum of levels is 192, in every match I play against players with higher sum of levels (>210) and I get +10 pints in most cases, and rarely more.

Just now a player with higher sum of levels (204) beat me and I lost -20 points, I beat him in revenge and gain +10?!

Another one with higher levels (209) beat me, I lost -15 points, beat him in revenge, and again just +10 points!?

It just doesn't make sense to me that you get so little points if you beat a player with higher levels.