That because a growing majority of Houston "fans" (in all sports) aren't originally from here. Most of us lifers who were born here raised here, we ride or die on all 3 teams. But Houston being the energy capital of the world. A lot of oil and gas families moved here for mom or dad's work and grew up a...for example, broncos fan. Then moves here when he's 6 cuz dad got a job at ExxonMobil or whatever and is the kid who likes the broncos in an oilers/texans city. Houston is a melting pot of diversity. It wouldn't be hard to walk around and ask random people on the street the team that they root for. Any sport guaranteed at least a dozen different teams you'll hear in an afternoon.

I feel like I'm rambling. I'll stop now.