Having looked at your games though, you clearly do not tend to do the objective thing and try simply for the win. When you support you don't appear to buy sightstone - number one glaring issue I have seen. To go off of that even more I looked over about 8-9 games and only one game did you buy vision wards where you bought 3 as malzahar. Vision won't show up in stats too much, but it is a huge thing for winning ranked games the higher you go. I can only assume if you don't do these basics then things like this are carrying over to other areas such as first tower secured, towers being secured in general. When to fight vs backing off and setting up a drag/baron. When to gank a certain area vs when you need to be around a certain lane to counter a gank.
I have a feeling though that you would rather just be told you are the "best mid in gold statistically" so I will probably end there.