You don't need to have a positive KDA to positively influence or carry game. It's quite possible that they were doing something different than you are which doesn't appear in their KDA, but led to them climbing more quickly than you have been.
If you want an example of such a thing, here is a match I played today while tired and making poor decisions.
I had a horrible KDA at the end of the game having gone 4/10/5 on Udyr jungle. However, despite my poor KDA, I was still had a large influence on the game and was a major factor in why we won.
- Even with how frequently I died, I still managed to double the opposing junglers CS (keeping my among those with the most gold and experience in the game)
- I managed to stay ahead in items compared to most of the enemy team to stay relevant and powerful.
- Even if I wasn't great in teamfights due to their lockdown and being behind, I was successful split-pushing to apply pressure my team could take advantage of
Heck, if you want another example, Proxy Singed was once a dominating strategy in which a Singed player would essentially feed to win. They would generally end the game with a horrible KDA but monstrous CS and influence on the game; they would just force the enemy team to deal with them while their team killed everything around them.
A players KDA isn't the only measure of their success; there are a vast number of factors, many of which can't be quantified, which will determine how a player has influenced a game.
Just because you don't know why your friend climbed more quickly than you did with a poorer KDA does not mean that they were luckier with teams. All it means is that you can't recognize what they are doing better.