Huge imbalance in this game. Free players are used as cannon fodder for premium players.
As a free player you're always matched against premium players with tanks that are 3-4 tiers above you and have absolute no chance of wining. You have a tier5 tank with ~450 hp and fight against a tanks with 800 hp that hits you for ~250 hp and you hit them for ~120. Then you get the tier6 tank with 800hp and you are match against tanks that hit you for 400hp. That about the hole idea of this game. It's not unusual to see 5-6 heavy tanks on one time and only one in the other
Sure, you might be matched against tanks for your own tier but that's very rare. Maybe 1 in 10.
It's usually one side with the premium players that wins and the other one with non-premium. This is just another pay to win game. Don't bother with it.