What happens to homefield advantage with no crowds?

This week, the Seattle Seahawks were one of the first teams to reportedly have some sort of contingency plan for the next NFL season given the complications caused by coronavirus.

Whether the NFL will run with full crowds (not a possibility many are still considering at the moment), partial crowds, no crowds, or even having games postponed and canceled, it’s all being considered. The Seahawks may be thinking of going at 50% capacity, roughly 20,000 fans, when home games resume according to Gregg Bell of the Tacoma News Tribune.

A league source with knowledge of their contingency planning told The News Tribune the Seahawks are exploring the possibility of playing their eight regular-season home games in a half-filled CenturyLink Field, because of social-distancing requirements in the coronavirus pandemic. That plan could involve leaving entire rows or every other seat empty, and decisions on which season-ticket holders would get which games as part of amended packages.

Behind the scenes the Seahawks are also considering home games with fewer than half their seats filled, with perhaps 20,000 or so fans. That would leave entire swaths of CenturyLink Field empty—and quiet.

The LA Rams are one of the teams that travel to Seattle every season and the Seahawks have a reputation for being dominant at home.

Reality has been somewhat different.

The Seahawks went 4-4 in CenturyLink Field in 2019, the same record they had at home in 2017. Over the last three seasons, Seattle is 14-10 at home, which is basically average. The New England Patriots have the best home record at 20-4, while the Rams have gone 16-8 at the Coliseum; they’ve been planning to start playing their games at the extravagant SoFi Stadium beginning Aug. 14 against the New Orleans Saints, but those scheduled dates have also come into question.

Perhaps though they’ll have better odds on the road, but that wouldn’t be easy as the Rams are 17-7 in the last three years away from LA and that is second-best in the league behind the New Orleans Saints. The Rams went 6-0 in road divisional games from 2017-2018 under Sean McVay and 1-2 in those games in 2019. However, that included a 30-29 loss in Seattle when Greg Zuerlein missed a field goal attempt and 34-31 in San Francisco when Robbie Gould made a final-second kick.

What will happen to the Rams — and every NFL team for that matter — if and when they play games with 0, 25, or 50% crowds? If nothing else, it could at least be an interesting experiment that could help teach us a lot about what goes into homefield advantage. One report has home teams winning games by 3 points on average (same as the default betting line adjustment for Vegas when it comes to home teams) and that they win between 55-60% of the time.

This became even more drastic in the playoffs, as home teams won 65.4% of the time in the divisional and conference round from 2002-2014.

If the NFL says no crowds in September, can they still say 25% crowds in October, 50% crowds in November, and 100% crowds in January if the world is a much different place by then? And would that be incredibly unfair to the teams who had more home games in September and October?

The Rams play only two home games in the first six weeks of the season, compared to four of their final eight after the bye.