I've been hunting the area all my life.The number one reason there are few deer is because most of the land is public-overharvesting.The lack of acorns in some areas and last year's winter played a very small role in it.
The deer that didn't survive were some fawns.A double wammy from Alt you could say.He says to shoot the mature does which leaves fawns which can't survive the severe winters,kinda like killing two birds with one stone.Being on the ground and actually in those areas I'd say the DPSM is below the 12 they're estimating.