It's still big on AO3 (quality is terrible though; lots of reader insert fics and English doesn't seem the first language of the majority of writers).

I think on the whole football fandom on tumblr is way bigger than hockey, but the rpf side is smaller than hockey rpf purely in terms of fic/shipping fandom. It seems to me that most hockey fans on tumblr tend to be rpf fans as well, which isn't necessarily the case with football tumblr fans.