How do you carry a team knowing that their collective winrates are 40%?

I had a 60% winrate climbing out of bronze 3 until there was a game where darius got caught out every single time an enemy went missing on the map. This is also the same darius that TP'ed to the tier 3 tower only to die to 3 of the enemies that we had watched take dragon and start backing to the base. This person is 0 and 7 for his placements. Riot just because I have a 60% winrate doesn't mean you can give me retards. Thanks