Can REAL Trolls be taken more seriously when banned?

I'm not talking about the trolls that refuse to support and go rengar "support" yet they don't carry a sight stone or help out the adc. I'm talking about the Trolls that pick trundle with clarity and clairvoyance when they are stuposed to be ADC yet they go down mid lane to feed a Katarina. In a ranked game no less.

I don't understand how someone decides to go rank and just Troll the whole game for absolutely no reason. He didn't speak in match make, no one was rude to him, and we were all pumped up and ready to win. I work really hard to get my rank up and after dealing with the lesser trolls for the past two days (afker's, support rengars, etc.) and finally almost making a comeback, I get landed in this kind of game. I lost 15 lp for that game and I think that there should be a way for the game to know when someone is just running in and dying. Perhaps if someone dies about ten times in five minutes then obviously they are a troll and the team is forgiven and perhaps only lose about 5 lp at most.