Your mental health affects the quality of your games and even if you do know this it is pretty easy to forget about it.
Sure plenty of players are going to skip through it but it should still be on there everyday you log in. Check yourself. Why are you playing? Are you playing who you want to play or are you playing a meta hero? Stuff like that.
And other tips like explaining what brawl, poke, rush, dive comps are. Again anything at all to improve matches.
Edit Overwatch is the only game I can think of that I played where you are very team-dependent on winning and your attitude is huge. Cod, Titanfall, xdefiant are more casual games I played