Well, the thing is, everyone has bad games. So, if you see someone at like 1650 with good stats and good everything, but they are doing shitty that game, I really doubt they overall suck, they just had a bad game. I've been in games where I'm like 0/3 in the first 5 mins cause I get fucking GANKED constantly. At that point, I'm like afraid to do anything, which leads to even more of a bad game as the game progresses since I'm missing out on exp and shit. Stats and PSR matter because it's overall, not just by one game. If you consistently suck in 500 games and your stats and PSR show it, then you're bad, that's all there is to it. If you are good in like 90% of your games, your stats and PSR will still be good, meaning you aren't bad.