During a GDC event Natasha Miller a research scientist gave a talk about how Blizzard is reducing abusive and disruptive behaviour in one of their flagship games Overwatch. We've all probably been there before when games get ugly, you're losing and people in the team are shouting at one another because they've made a mistake or they're perceived to be a "noob" and all other words under the sun that relate to the person not being a good gamer...
In her talk Natasha Miller said that Blizzard has reduced disruptive behaviour by 40% via their endorsement system. The system gets players to rate others who are good teammates and this means that you give our endorsements to reward good behaviour, instead of creating a reporting system which just generates a lot of negativity. Jeff Kaplan said that abusive chat in competitive games had dropped by more than 26% in the America region just after a few weeks of the system being implemented.
With the system bringing about levels too, and randomized loot drops it creates a positive reinforcement of playing good to get those consistent endorsements from your fellow players and if you don't your level is going to slip and no player wants to see their level drop.
There's still a lot of work the team want to do and it will be interesting to see how they develop this even further in time to stamp out that negativity in game.