One thing I never got to learn

Diamond 2-Platinum 6 player here (currently Plat 5 after having abandoned the game in May, I played every week since day 1) and I want to get some tips on how to deal with players hitting a 5 perfect shot while strafing and crouching the opposite direction than me.

Like, how the hell they can get the reticle on me if we are going opposite direction and strafe makes it going left and right? I don’t think they switch to RS aiming while strafing since it’s nearly impossible to be precise at that level. Maybe someone can give me some tips or explain which is the best way to deal with it? After 6 months it looks like I completely forgot how to do a 1vs1