Fewer offensive holding penalties (462) were flagged in 2020 than in any season since at least 1995 (and there were two fewer teams back then!). A two sigma difference from the 2002-19 mean. Just one way it's increasingly impossible to play consistently good defense in the NFL.

Meanwhile, defensive coverage penalties remain very high (though slightly down from last year's record level), and defensive pass interference hit an all-time high as well (2020 is 2+ sigma compared to both 04-19 mean and 15-19 mean). More than twice as many DPIs compared to 2007

While teams draw penalties at different rates, there's obviously a substantial element of randomness and arbitrariness to it. The upshot is that offenses are increasingly exposed to significantly fewer bad penalties and significantly more good penalties (roughing is also way up)