SleshWell for example mge : when i recon someone that i usually beat (easely or not whatever) and they crush me, i get frustrated cause i know i'm doing shitty strafes, my aim is bad atm ..., but i don't rly think i'm worse than them, jut "bad atm".
There's your problem. You're frustrated. People underestimate how much frustration and fatigue can factor in your performance. It's important that you stay calm and don't let shit get to you. The calmer you'll be, the better you'll do overall. Also make sure to not play for too many hours straight. I usually hit my skill peak during the 25%-50% of that day's playtime. Afterwards, it just goes down-hill.