Hello,
In small scale games (less than 12 units per side), where the units are all predominantly the same type of units (Mostly Mechs, Mostly Tanks), the Force Size rules in Tech Manual (pg 314) are very effective.
Force Balancing does not work well in larger games or when you are using a very mixed combat force. Particularity the use of infantry, BA or Protos can slew your final BVs a bit. With experience and agreement of all players, these units can be used with player agreed to tweaks.
Best,
Joel BC