Also: I don't get it how Vault 87 keeps producing Super mutants? Only way in and out is blocked... Maybe it's something which can't be explained with reasoning and logical thinking (=Bethesda's illogical screw up).
No, it's obvious Vault 87 isn't the location of the Vats any longer - assuming they're even using Vats of the stuff this time around anyway. Only reason the Master was using the Dipping technique was because that's the way Richard Grey got exposed to the stuff.
The background info on the FEV in all games suggest that testing was done via injection - and in Vault 87's case, it appears to be airborne inhalation given the vents in all the testing chambers.
Also the residents of Little Lamplight all point out that the "monsters" don't come out of the Vault anymore.
As far as Im understanding it, the muties we encounter in the ruins are the people from Vault 87. I dont think they capture people to transform them, at least I have not found solid prove to that. I think they want to eat them rather to transform them, talked to some prisoners I freed from them and one was talking about how they wanted to eat him. Another prisoner, I think Shorty was his name, was also about to get eaten as I bumped in. W
It's possible, especially given the Gore Bags that accompany Super Mutant infestations.
But during the rescue in the Police Station, they make mention of taking Red "with them" when they "go home". That to me suggests that there's at least some policy in place by the DC Muties to increase their numbers. It would also explain how the Brotherhood of Steel could have been fighting them for 20 years and still not see a significant dent in their numbers.
I think the Behemoths are Vault 87 dwellers (As the BOS mentions that the DC Muties get bigger with age), but I honestly think there's some process out there to turn normal people into Super Mutants. Especially since the FEV was showcased in several cases on the West Coast to enhance intellect. Combined with Fawkes learned attitude, I can't see the DC Mutants not having at least a FEW intelligent leaders out there.