From the Washington Post:
By Adam Kilgore and Neil Greenberg
January 14, 2022|Updated January 14, 2022 at 9:20 p.m. EST
The experience of soccer teams playing in front of empty stadiums during the pandemic suggests that the home field advantage is mostly due to cheering.
Visiting teams used to have objective disadvantages such as small, lousy locker rooms, but most more modern stadiums assign ample facilities to visitors. (In baseball, in contrast, since the 1990s, stadium design has favored quirky outfield fence angles to give the home team an advantage.)
I’m not, however, wholly convinced by this graph that there’s been a permanent decline in home field advantage. NFL home teams won 60% of their games as recently as 2018.
One other thing that is going on is that there have been three recent moves of NFL franchises, all to tourist towns with lots of visitors in the seats rooting for the visiting team: the Rams and Chargers to Los Angeles, and the Raiders to Las Vegas.