A tumultuous year had the TV industry waiting anxiously for the return of football -- both NFL and college -- this fall. And while there's been plenty of football to watch, the story is increasingly all of the football you can't see.

This past weekend, the NFL announced numerous switches to future schedules after positive COVID-19 tests around the league. College football has been shifting schedules around since August, and continues to do so each week without a centralized standards for testing. The common theme for both? The lack of a "bubble" keeping players and personnel in a controlled environment.

Aside from the obvious health concerns that can come about from an outbreak of positive tests, the constantly shifting schedules also become a major headache for networks. Premium inventory is getting pulled just days from kickoff, without much in the way of capable replacements. The NFL only has a finite number of games each week, after all, and only so many compelling matchups for national audiences.

Meanwhile, college football is more dependent on marquee names and a loss of big matchups leaves little in the way of comparable games. That's always crucial, but it's even more so now with just three power conferences (ACC, Big 12, SEC) in action at the moment.

College football and NFL decision-makers seem content to charge through despite these shifts; they'll rotate schedules and continue to have teams travel each week despite the increased transmission risks. But realistically, both are a major outbreak away from a serious scheduling quandary. With teams only able to play a game per week, there's only so much flexibility available. The NFL, in particular, has the additional challenge of the Super Bowl being pretty locked into its February 7 date. Even without fans -- TBD -- the logistic requirements of the world's biggest media event are also difficult to just push out another week, even this far away from kickoff.

The solution, potentially, would be the one that the NBA and NHL just implemented successfully: the "bubble." Each league embraced a gradual restart with all players in a specific market (Orlando for the NBA, Toronto and Edmonton for the NHL), and respectively wound up with zero positive tests throughout. Granted, those were both for the playoffs and not the regular season. But keeping players contained and safe provided compelling game inventory that was predictable for both networks and advertisers -- which is ultimately what they wanted most out of the return of sports.

MLB, after positive test issues early in its 60-game season, wound up locking things down late and then pushed its own current playoffs to bubble settings as well. We've yet to see positive tests for baseball since the postseason started earlier in October as well.

For college football, I think the train's already left the station. With so much inventory confined to ESPN-owned networks, they'll shuffle what they need to given the high volume of games each Saturday. Decision-makers at the school, conference and network levels have accepted the risks at this point, so it seems like the season will reach a conclusion by late December, even if it's a disjointed one.

The NFL should be looking at college football's situation with some caution, however. With new positives seemingly appearing every day for NFL rosters, the league is nearing a tipping point that threatens its ability to complete a full schedule in a timely fashion. The NFL has less inventory and days to play with vs. college, plus increasing limitations around days/times games can air now that primetime programming is returning on networks. College football can just toss a game to a Wednesday night on ESPN if need be. Not so simple for the NFL to just shuffle to whatever day given network contracts and an upcoming (contentious) election taking up a ton of attention as well.

While it currently seems unlikely a bubble happens, positive tests could get to the point where college football and/or the NFL may not have a choice. The NFL, in particular, has fewer teams and smaller rosters. They're also dealing with paid adults, so the "bubble" format is also a bit more tenable there. The pressure to get that done won't come from owners, however. And it may not even come from the players, either. Realistically, it may be TV networks and brands that start banging the drum for stability should the NFL start seeing mass rescheduling on par with what we've witnessed at the college level.