Thoughts... what you say and what you ASSUME can often be correct... but not ALWAYS.
If they're on a loss streak, they are probably HIGHER elo than you and are thus playing against opponents who are rated to be weaker than them when they are performing up to par.
Loss streak doesn't always have to do with the player... they could have an unlucky streak of TEAMMATES feeding in their games and throwing to drag THEM down.
Kda does not tell you nearly as much as you might think. I've seen fed teammates singlehandedly throw the game by greeding for kills instead of playing the map and getting objectives... leading to trading kills pretty often, feeding away shutdown gold several times, and ultimately costing the game. I've seen other players be tilted in lane, feed, but NOT intentionally feed because they turn it around, LISTEN to their teammates, make smart plays, and while their kda at the end isn't amazing... they definitely pulled their weight considering how they started the game.
Aside from an example like that last one, people can play the Darien game. I'm gonna be the distraction, sure I'll die every fight, but I stay relevant vs my opponent despite this, force you to camp me with multiple people, and lose the entire rest of the map to my team because they get a 4v3 or something like that the entire game... just for you to keep me in check.