First off, the game isn't just about individual performance. Yes individual performance can make a big difference, but I have seen games where a team's composition really didn't shine until the team fight phase of the game. It is possible for every lane to do well and still lose mid-late game.
That being said what is not shown are the picks/counter picks. This plays a lot into how the end result will be. For instance I see you have several Katarina games - if the other team had someone with suppression focusing you every team fight, even if you started 5-0 you could still end up with an overall decent KDA but lose the game. Also things like positioning during team fights, when you choose to move as a group or go farm a lane, fights over baron and buffs, and what items you build invariably alter the course and result of the game. And if the team doesn't function as a team (IE initiator goes in without the rest of the team, people don't group up, no map control with wards, etc), then you give the other team an advantage despite the KDA.
Yes sometimes you can get throwhards that just don't know their 'R' button from their 'B', but the elo system isn't about short term gains/losses, but the long term. My advice is if you are stuck in a lower elo bracket and you know how to last hit, go adc. It is simply the easiest way to make or break a team fight late game.
Pick ADC, farm hard. Communicate with the team to coordinate ganks, wards, pushes, backing, and fights over buffs. Call your mia, invest in wards yourself regardless of what role you are if needed. Buy items that respond to the other team's champs and item builds. (Penetration where needed, survivability, items that allow you to perform your role without dying - or if you are going to die, make sure you can take out 2-3 of them with you or enable your team to win).