Not really that surprising, and it's not really got that much to do with a loud minority of kids on the Internet being upset at women in a WW2 videogame.
Just simply look at the history between both franchises, as well as what's releasing during that period.
Battlefield 1 launched next to arguably the worst *ever* Call of Duty game in terms of fan reception, Infinite Warfare, and still managed to get handily outsold.
The Black Ops series has always been the biggest sub-series for Call of Duty. Battlefield V is sitting in a WW2 setting a year after Call of Duty sold it to well over 20 Million people and 2 years after they were praised for originality with WW1. On top of that, they're releasing it at a completely fucking idiotic time. One week after Black Ops 4 and one week before Red Dead Redemption 2. It's gonna get eaten alive. September has Spiderman and FIFA. October has Black Ops 4 and Red Dead. November has Fallout 76. That's a lot of competition for a bland shooter doing nothing new.
