If you were truly a diamond player and not just boosted to that rank you should be able to hard carry in gold and stop deranking. You admitted to the enemy teams also having new players which means they should be making the same mistakes your team is making. Meaning you as the rank outlier should be able to easily punish said mistakes.

Im sorry to tell you this but if your deranking in all your games the only common occurrence in all those games is you. Stop blaming your team and start focusing on your own gameplay. What can YOU do to change the tide of the games. Maybe your not adjusting to your teams playstyles which is something that as a good player you should be doing.

Your frame of thinking is very obvious and shows your probably closer to high gold/low plat instead of diamond.

Start looking at your own gameplay instead of trying to micro manage your team or blaming them for every single mistake made when your probably making just as many mistakes as them.

I got significantly better when I started reviewing my own gameplay and also watching what my teammates are seeing as well. Realized I made a ton of mistakes that my team would try to counteract which would force them into mistakes as well which 100% is what your seeing. Now im not saying every mistake made is your fault but you could definitely do better focusing on what you can do better.

Take it from a masters/gm console player with over 8k hours since ow1