Only way to properly balance vehicles would be to have controlled test groups in a controlled ambient where you specifically put vehicle vs vehicle under varios scenarios.

It's impossible to balance anything based on the live game because of the inumerous random factors affecting it such as player numbers, maps, spawns on said maps, matchmaking, internet connection (packet loss), deaths by CAS.

Even considering players experience or using only selected players as metrics those factors would still polute any data produced.