I was diamond 3 in season 4 and since then I've had a steady decline usually tilting down to plat 2, last season I ended on plat 5. Had huge ego issues about it, didnt think I belonged there, raged at my teams. Truth is you have to learn to get over it and just accept you are where you are and there's always stuff you can do to improve.

Maybe it's muscle memory, maybe you're not playing as much, or maybe you've forgotten that being high elo isn't fun, it's about winning, improving is not fun, why would it be? I love playing on autopilot, I don't have to think I just instinctively play and rely on my mechanics. However, that's bad, when I understood I was just being complacent for 2 seasons it made sense.

I got placed in gold 4 this season, and since then I've had a rapid climb all the way up to plat 4 80 lp with a 60% win rate and crazy kds, the game just suddenly got easy again once I started applying pressure and thinking while I play, and playing a lot more of course, you'll get it you just need to focus a lot more.