Direction and focus of balance

When it comes to balancing, there has been rather large divergence in the method of implantation in what and how something is changed.
Not that this is good or bad, but there does seem to be a random factor in some of the changes that are being made. I guess this is because the FAF is a collaboration between individuals with different ideas and mindsets.

For instance there is a trend of normalisation, such as making each unit useful for its cost and class, either shifting its power up or down (e.g. mantis made slower and same cost as other t1 or beacon more range and cheaper than it was).

Secondly there is the direction where other units are statistically worse and are compensated for with the strength from other units, sometimes even units of different tiers.

And third there is the direction of units being worse or better statistically because it makes the game more interesting or asymmetrical.
What I want to ask is what decisions lead to how these are chosen. And when is one argument for a direction better chosen over another?

I would like to know as well.

Analyze, Adapt, Overcome...