Dear your average hidden MMR should be around 2.5k to 2.7k now. There are few suggestion which I can give you to improve on both the accounts.
1. try to participate in team fights, but do not tank. Stand near team fight and once team you see any enemy hero at low HP, kill him and then get away from team fight at a safe distance. You can keep repeating this thing for whole team fight.
2. Spam those heroes which are your best. Because of which you can win matches easily and get great KDA.
3. Try to get as low deaths as possible. If you want to move to next skill bracket, this is the best solution IMO.