BF4 was considered the beginning of the end at launch sure, but by the end of its lifecycle it was pulling huge numbers and great reception. They had basically FIXED things like bad netcode and many more fixes that made it the best battlefield had been yet imo as bf3 lacked grander scale in terms of mechanics and content

Bf3 not being bad company 3 was an issue pre launch, but almost immediately people stopped caring because bf3 is almost universally beloved now for its huge balls and incredible rush map design and more enjoyable vehicles than Bad Company

And finally, it's not about the quarter.. the release date is literally only a week after BF1 and CoD was already pulling in huge fps numbers about a month before. It's been observed many times before too that people tend not to buy multiple games before Christmas, and often will only have one or two games to choose from for Christmas.. which means nobody is taking a risk on Titanfall 2 (both for the reasons you stated, and because of the release window)