You need to stop saying "before the rank system update" That was what, almost 2 years ago at this point? Let it go, it's no excuse anymore. And yes, it was higher ranked before because the upper ranks were inflated with people not really belonging there. If your goal is a high rank, you simply need to get better. I went from MGE before the update, to MG1 after, to Supreme/Global now (bit up and down, since these ranks are a fucking mess of cheaters) Higher ranks aren't impossible, but it gets significantly more difficult if you lobby with all kinds of ranks. Either go solo or find equally ranked teammates. Mixed lobbies are a hot mess with Valves rating system.
As two question 2: It's called having an off game. I simply love how everyone acts as tho they're dropping 30 frags every single game they play. Even some of the best pro's have games where they're just off.