Doesn't change anything, I'm mostly the second best and sometimes first, and my KD is -0.3 which isn't even bad, 222 kills and 272 deaths.
The truth is that there are seriously bad players in halo 5 and i get teamed up with them.
It does change things. If you're getting the most or second most deaths in the majority of your games like I previously mentioned, then you're actually hurting your team when you don't go positive and you aren't the best player like you claim. I'm not saying you don't get worse teammates, but you aren't exactly the best all the time either.
I also looked at your last twenty Slayer games and only seven of them were outside of a ten kill difference. That means that more than half of your games were evenly matched even with terrible teammates. That's something you should think about more.