The biggest issue is not the scaling level system but the fact that it's scaled based on your commander and not your tanks, If you keep getting better tanks then your commander will out level them by a lot. My average tank level is only around 30 but my commander is 42, so invasion missions are very hard and anything my commander level or higher is next to impossible to pass.

If we had another way to level tanks so the commander didn't keep out scaling them, that would be better.