Build time was increased because the price for requisitioning Cpt/Ltn got 20 fuel cheaper, meaning they come out almost one minute earlier assuming a fuel bottleneck, which translates to 40-60 seconds in the game. USF can float a bit of fuel at this time with a standard 3x Rifle build, still this doesn't delay you for a full minute.
I don't know the exact build times before that patch, but by gut feeling anything that delays the officers for 30-40 seconds is probably sensible.
With the .50cal you mean the sprint removal and slight suppression nerf back in 2018?
The suppression change is a token change, the weapon suppresses super quickly anyway. Sprint removal is indeed a nerf, but a good one. A flanked MG should be properly countered at that point, it should not be able to just run away from the danger.
But as time, another faction could already build up next tech or get more men on field ( due to new officer has to spawn outside map, not on base.
Also .50 cal nerf set up time is a biggest hit since it always clumsly (sometime it take 1 burst some time it take 2-3-4 burst to suppress a single squad. That why a blob LMG can delete them) As least Maxim or Vicker could do something and retreat. They also not give .50 cal anything back to justify a nerf.
Talk about USF openning. they depend on Rifleman too much (2 rifle to rush officer or 3 rifle and officer, sometime 2 rifle and a mortar). As same time, OKW, WEH have more solutions.
Also Kubel is a thing. Unlike Sov, UKF, WEH, or even OKW. You dont have any thing to actually fight against it. This 200 mp can do various thing like bleeding, bait, push out of cover, back capping or even hackmap at vet 1.
in 2v2 and abrove, Kubel is massive unbalance unit that can simply deny a whole faction style and forcing them to pick a specific doctrine to deal with it such a Mechanize, airbrone. a combine of Kubel hack map and indirect fire is such a pain in an ass.