How to deal with people who refuse to play?

Hey guys, how do you deal with players with refuse to play? I'm on a 10 game losing spree, and almost every time, it seems someone is crying or throwing on my team after losing one team fight.

One game it was 22 min, 20-21 after losing one team fight, our pos1 Luna just blames everyone. I reassure them it's fine when I was doing relatively well (6-0 as the pos2, helped gank safelane when asked), but Luna proceeds to destroy all their items and walks down mid. After checking the repay, the NW on both teams were pretty much even.

In another game, our pos5 Venge refused to ward. I ended up buying them and warding myself as a pos2 (ended up buying 14 wards towards the end). In team fights, they refused to stun/swap and proceeded to farm neutrals. Swapping in the carry to save themselves when they got caught.

People seem to not play their roles very often in this bracket. Kunkka pos4 not warding and going carry, Lina pos4 stealing farm from the carry, Riki pos5 with meteor hammer and ksing with pounce… Been seeing it all too often in my recent games.

I avoid typing in chat now as I know the slightest things can set people off. But honestly, how do you climb in rank when there's always someone refusing to play? I'm in the Crusader (USE) bracket, but even Guardian was better… Never had a game where someone would just run down mid in Guardian.