Sports fans know that referees can often sway the outcome of a game -- for better or worse. There have been allegations of impropriety among NBA officiating crews. MLB umpires often have their own personal definition of the strike zone.
Yet people don't often question the same aspects of NFL referees and their crews. Maybe that's because, for the most part, the zebras are anonymous -- changing cities every week and rarely making a call worthy of a headline.
But so many penalties in football are just split-second judgment calls. Is a questionable pass interference any different than a slider on the outside corner or a foul-or-flop call in soccer? It would stand to reason that, like in those other sports, NFL referees would exist on a spectrum of strict to loose.
Some guys are going to call every slight hold, every hit on the quarterback and every ticky-tack hand jousting between cornerbacks and wide receivers. Other umpires are going to let those things slide.
With that idea in mind, let's look at which referee crew (the same group works together all season) calls the most total penalties per week in the NFL:
Most of the names on the list are relatively anonymous. Perhaps the most famous referee in the NFL, Ed Hochuli, also happens to be by far the most strict -- by an average of one more penalty called a game than the next highest, Jeff Triplette.
Hochuli's crew also calls an average of five more penalties a game than the two most lenient units, headed up by Pete Morelli and Scott Green. That amounts to a difference of about 50 penalty yards per week. Over the course of a season, that's 80 extra penalty calls and 800 yards of game-changing decisions.
This data isn't perfect. It doesn't take into account penalties declined, and obviously there's a certain amount of variance to these number over the course of a season, even with the crews rotating around the country.
Even so, it can give us a window into something the NFL will never admit: that there is a significant difference between referee crews -- enough to alter the course of a game any given week.