When I started playing the server without any power upgrades or ranks, I managed to get to level 17 at one point and use the AK47 'Paladin' special weapon. This special weapon is unique in its own way that it has barely any recoil, shoots and reloads relatively fast, and deals a reasonable amount of damage even without any power upgrades. At no point should 'beginner' level players be made powerful enough, it's intentionally made difficult at the beginning to make the progression system seem more appealing or addictive (the more upgrades you have and the higher level you are, the easier you will deal with the enemy opponents). Even without any of these upgrades or ranks, I still managed to get a decent amount of kills every single map. The point is that there is a distinct difference between different skillsets and being overpowered altogether, as you might not have the most powerful weapons, yet have a decent aim but still manage to have a decent score at the end of the map.
Tank is not overpowered, it is specifically designed to cope with higher-level players. Nerfing it would mean that higher-level players would become even more powerful and more difficult to deal with. Nothing can be perfectly balanced.
