As someone who has climbed out of silver V 3 times now (only to fall back down), the winning team in a ranked game down here can be easily determined in 3 ways:
1) Did the jungler die in his first post-clear gank? If yes, GG. That lane advantage and jungle disadvantage will be enough to crush the enemy team, or at least their morals. The jungler will blame the lane, and vise versa. Either way, if you jungle, remember it is more important to not die than it is to get a kill in a gank. Making your presence known can sometimes be enough.
2) Did the snowbally assassin get fed? If yes, GG. People down here are frustratingly one minded. The bruisers will get "AD carry" in their head and attempt nothing else. The AD carry will get "escape their assassin" in his/her head and attempt nothing else. No one will peel. No one will focus. It's all over.
3) The number one most deciding factors in ranked games are: ****ty engages!
You will never, ever, ever, convince your team to right click on top of you. Ever. I have begged, bribed, bemoaned, belittled, and in one particularly rage inducing game, betrayed my teammates, all in hopes of getting them to not go where they wanted to go, and instead all go to the same place. It won't happen! That amumu who got two perfect engages in a row? Will get caught at wraiths over and over and blow his ult to try and escape. Your legendary AD carry? Will die pushing bottom.
It sucks. You'll lose. Sorry.