When i mean bad, i mean literally, not trash talk, bad manners and stuff like that. If that player is just bad, what are you supposed to do? If you doesnt notice stuff like counter ganks, babysits, positioning, are you supposed to point it out? Because from what i've experiences, when ever i point something out people take it offensively and i really have no idea what to do.

some poeple just have bad games....i literraly just watched a stream of dyrus get completely wrecked top lane....

hard to judge anyone on one game.

and its that.
one game.

Put them on ignore. Duo queue. Carry harder. My duo and partner and I carried a game where we had a 4/14 Warwick and a 3/10 yi. You can only control what you do. So just play your best, do all the stuff that you're supposed to be doing and even do the stuff that your team mates aren't doing. Like for instance if you're adc and you notice your support isn't really warding. Buy a few wards. Or you're mid and you pushed your mid opponent out of lane. Top is hurting bad, but jungler hasn't ganked top. So you go gank top. Stuff like that. Just try to be a team player and do everything and anything in your power to make your team win. I had a game I played Ashe and my support was pretty bad(Volibear). He ended up taking 3 or 4 kills from me early. If any of you have ever played Volibear, if he gets fed he's almost unstoppable. So I stepped into more of a support role with Ashe and we won the game. Could I have raged and called him a nub for taking kills? Sure. Would it have won us the game? Probably not. You have to put your ego aside and go into the game knowing you are going to do whatever it takes to make sure your team wins.

I dont mind criticism when playing or pointers. Of course some people will get pissed but others won't. It also has a lot to do with how you present it.