The updates Every update which adds new weapons makes the game more unbalanced. It didn't used to be so bad when the weapons rewarded skill. The ambassador rewarded players who could aim by doing more damage on headshots. The kritzkreig made the ubercharge more versatile but gave up the invincibility and made the medic vulnerable while the charge happening. But then Valve started making weapons like the backburner, which has a very small drawback but still gives you increased damage as well as crits from behind.