I've been conducting my own study on how boosts are calculated, and applied.
I created two new test accounts, used two control accounts, and two older accounts.
I acquired some of the various boost units over the past 90 days.
I made sure each account acquired the same boosts.
I won't bore you with all the nerdy, scientific details, just the facts.
If you acquire a boost unit that implies a 10% Infantry boost, for example.
Your unit will get almost a 10% increase in defense.
However, the attack increase is not .10, it's .001.
In some cases, it is not .10, but .01.
Consistency is a rarity, ain't it? LMFAO
Sadly mates, in either case, the attack boost is insignificant.
That is why the delta between attack and defense on newer accounts is about 1:3.5 or closer to 1:4.
Its hard to discern the delta on older accounts, unless you measure and study the account's growth.
I suspect this was done for three reason: appease the older accounts, ignorance of math, keep newbies from overtaking oldies. LOL