From recent videos released by WG it appears that the developers attempt to balance (or even rebalance) the game using DATA rather than opinion. This is a good thing.
However, the data is wrong when it comes to armor effectiveness as shown in the vehicle statistic 'Armor Use Efficiency'. Why? Because 'critical hits' (which usually do no damage) don't count as damage blocked by armor – which is illogical.
Example: you fire at a tank and track it, doing 0 damage…. it's just a 'critical hit'. However, the stats don't reflect the blocked damage. Look at the stats of any light tanks and you'll see the armor use efficiency will be close to zero, yet those tanks will have been tracked dozens of times, even, in some cases by TDs that can deliver 1500+ dmg. Hitting a small light with a high alpha TD round and doing no damage is ridiculous.
The bottom line is that this critical hit mechanic needs a rework but it flies below the radar because the data doesn't show the mess it makes, so the devs do nothing about it.
Source: https://www.reddit.com/r/WorldofTanks/comments/f5aspu/critical_hit_needs_fixing/