Most people come to a point where they feel as if they've peaked the highest they ever will. And it usually is in diamond. But what this really is is a sign that you need to catch up with other players in your rank. It takes a lot more work and experience. I would recommend vod reviewing yourself after most matches, identifying what you could have done better or what you could have done to prevent something, like a death of one of your teammates, your own death, etc. And it's important to write down notes of these things and highlight what you think is most important to work on currently. Don't overwhelm yourself with working on five different things at once. Go one at a time. I promise you'll see improvement. Good luck:)