The problem with this PSR is that it introduces multiple points of failure, in that every action that you receive match points for could be not valued correctly. Are we going to have threads like "TAG assist should be worth 5 match score instead of 2 so that I get a better PSR rating"?
Win/loss is not subject to faults like this. If you're in a group that carries you, it's still very easy for you to get a high match score as you deathball over a routing enemy that doesn't put up good resistance, so it still has the same possible problem. In particular, light mechs tend to get much higher scores during stomps as they have the speed to take advantage of out of place/unsupported enemies.
With win/loss if you had a group of 11 good players and 1 bad, they would lose against teams of 12 good people, so their Elo would still be beneath a good group of 12. Then if you're that 1 bad, anytime you play outside of your group of 11 good friends your Elo would go down without them there to support you, so it corrects itself.
If you play with better people, you're going to get a better match score because you'll tend to win more, so you'll still get carried. That won't change.
I don't think this change is going to have the effect people desire and we've introduced potential balance problems with the amount of match score actions give.
Also there's generally a large disparity in match score between the weight classes as damage/fighting tends to offer higher rewards than anything else.
Edited by oneproduct, 17 August 2015 - 03:34 PM.