I went 2L-4W-1L-1W in my 8 games for mid lane. My first loss was in part due to my jungler who died early, got tilted, and went AFK. My second loss in part due to my top laner who wanted to try the inting Sion strategy out and ended up feeding 12+ kills to Jax, who then proceeded to 1v3 and 1v4 our team multiple times. My third loss was in part due to my top laner who first timed Renekton into Jax, gave up first blood, died 3 times solo before 7 minutes, and then also fed the jungler and mid laner because he would constantly push the wave into the enemy's side of the lane, ending 0/11/2.
On the other hand, for my 5 wins, 3 of them were more even matches, while the other 2 were stomps on my teams side, with certain members on the enemy team having abysmal KDAs.
Unfortunately, the worst members on your team (and the enemy team) tend to determine the outcome of the game. There's not much you can do about it in solo/duo queue.