Data Visualizations About Referees From the 2024 NFL Season
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What’s up everyone,
Today’s write-up will focus on The Law. That’s right, we’re focusing on the real stars of the show in the NFL, the referees. I went through every NFL game from 2024 and grabbed the game’s referee, umpire, down judge, line judge, back judge, side judge, and field judge and we’re going to try and find some patterns.
Analytics Content I Enjoyed This Week
This article from
about the NBA season was great. Helped soften the blow of game 7’s letdown. We were robbed of an all time classic, I’m afraid. Check it out here. He’s always making great stuff and his R visualizations are very inspiring to me.- published a good article about NASCAR analytics, I don’t think I’ve seen many NASCAR data visualizations lately but I enjoyed it. Check it out here.
I loved this podcast from
about College Football 26. Check it out here.I enjoyed this write-up from
about the NBA Draft. Check it out here.
So What Do The Refs Actually Do?
I watch a ton of football and I had to look this up, so I thought I should share it with my faithful readers too. Most of this info I’m giving you is from the NFL’s official website.
The Referee
The Referee wears the white hat while the rest of the judges and umpires wear black hats. They’re the boss, the sheriff, the head honcho, the ones under the microscope by the social media-verse.
According to NFL.com, the referee has a few differing responsibilities.
Run Plays
Pre Snap
Monitoring the QB and RB for a potential false start
Post Snap
Watches the C, RG, and RT for “…their actions and those of the defenders engaged with them.” So they’re looking for holding, illegal hands to the face, etc. for the right side of the offensive line.
Pass Plays
The same responsibilities as listed above, plus…
“Turns attention solely to quarterback as the defense becomes a threat.” Insert your favorite Patrick Mahomes joke here.
“Primarily responsible for all action around and to the QB/Passer.”
“Rules on Roughing the Passer, Offensive Holding, Pass/Fumble and Intentional Grounding.”
I’ll skip the special teams responsibility descriptions for the sake of time, but make sure you check out the link above if you want to read them all.
The Umpire
The Umpire is mainly responsible for determining if the thrown pitch is a ball or strike as well as ejecting any players or managers if needed. My bad, wrong sport. The football umpire is concerned with reviewing player equipment, counting the number of players on the field, and they decide who has possession of the ball after a fumble.
Run Plays
Pre Snap
Watches the C, LG, or RG for any false starts. Some overlap going on here?
Post Snap
Watches the C, LG, and LT and “monitors their actions and those of the defenders engaged with them.” So the same as the Referee but they watch the LG and LT instead of the RG and RT. But both watch the Center.
Pass Plays
Same responsibilities as above, except with the added aspect of assisting the Referee “…with ruling on action around or to the QB/Passer.” So it looks like the roughing the passer penalty is a group effort.
The Down Judge
The Down Judge oversees the line of scrimmage, directs the chain crew (need to update your website for this one, NFL.com), watches for offside and/or encroachment, and lets the referee know what down it is.
Run Plays
“Watches for false starts, offsides, or encroachment along the lines”
“Watches blockers and defenders on the nearest side of field for any penalties.”
Determines when someone goes out of bounds
Determines forward progress
Pass Plays
NFL.com for this one says “Based on the formation, they are responsible for specific receivers.”
“If play goes into their vicinity, helps to rule on whether pass is complete or incomplete.”
“Rules if receiver is in or out of bounds when catch is made.”
“Rules on offensive and defensive pass interference, defensive holding and illegal contact of eligible receivers.”
“Determines if pass is forwards or backwards on passes towards them.”
“Makes sure passer is behind LOS when he throws ball.”
So the Down Judge is watching the passer while simultaneously watching for any PI(s) or holding(s) amongst the wide receivers and secondary. Sounds easy enough.
The Line Judge
The Line Judge, like the Down Judge, “Watches for offside and encroachment” and “Counts offensive players on the field.” However, they’re standing on the far side of the field while the Down Judge is on the near side. Their responsibilities are exactly the same as the Down Judge except the Down Judge must always know what down it is.
The Field Judge
The Field Judge stands back from the Line Judge, and they “Watch receiver split widest on nearest side of the field for illegal use of hands and blocking fouls, and for penalties on defensive back covering him.” They also count the number of defensive players on the field and determine if plays in their direction go out of bounds or not.
Run Plays
“Watches widest receiver block, looking for illegal use of hands or holding.”
“If play goes to nearest side of field, determines if runner goes out of bounds.”
Pass Plays
“Focuses on widest receiver on nearest side of the field to make sure the player is able to run his route without defensive interference.”
They also watch for complete/incomplete and PI if the play goes in their direction.
The Side Judge
The Side Judge is the timekeeper if the game clock has an error. They stand behind the Side Judge and watch receivers in the same way the Field Judge does, just on the opposite side. They have the important added responsibility of signaling to the Referee whenever time expires at the end of each quarter. The rest of their responsibilities are the same as the Field Judge.
The Back Judge
The Back Judge is the Free Safety of the referee crew, standing way back deep in the middle of the field. They keep track of the play clock and manage commercial breaks.
Run Plays
NFL.com says they “Start in the middle and read the initial action by the LG, C, and RG.” And “Once a Back Judge reads run, focuses on the first-level action looking for defensive holding.”
And “Finally, they go to the primary threat of foul.” I’m not sure I know what that one means.
Pass Plays
“Once the Back Judge reads pass, they go to the #2 or #3 receiver based on the formation. Once the ball is released, the Back Judge immediately foes to the receiver where the pass is thrown.”
After that, the Back Judge “Decides if receiver made a legal catch.” And they also look for OPI, DPI, defensive holding, and illegal contact.
Alright, easy enough. Did you get all of that? In short, what this means to me is that it’s very hard to blame a foul on a specific referee, umpire, or judge when it occurs. There are some key data gaps missing and too much overlap. Almost anyone can call a holding and without tracking/formation data, it’s hard to assign blame to individuals or determine who exactly threw the flag. So how can we proceed? Is that the end of the write-up? Of course not. We can look at referee crews as a whole and try to find any patterns in their penalty calling.
The Crews
So with all of these different positions for NFL officials, how many different combinations do we have? Do they usually stick with the same crews? And if so, do they stay in the same positions within their respective crews? Let’s look at a simple knitr output table to investigate:
Craig Wrolstad runs a tight ship. His squad all occupied the same positions 17 times last season. I really tried to make a visualization to capture the different NFL officials and how often they worked together but I couldn’t capture what I wanted with it. Here’s a B-Side version of a chord diagram I tried.
It’s important to share stuff like this to show you that everything’s a work in progress. And sometimes with data visualizations you swing and miss. Here’s another idea I had, a table as long as a CVS receipt to show the different positions NFL officials covered:
The conclusion you should draw from this chart is that NFL officials do not play multiple positions. Even though they have similar roles and responsibilities, except for two officials who are able to play both Side Judge and Field Judge. Usually, you’re either in at your known position or you’re out, as illustrated by those on this graph who only officiated one game like Daniel Gallagher.
Trigger-Happy Sheriffs
So which referees called the most penalties last NFL season? Let’s look at these tables to find out.
One thing that stood out to me was Craig Wrolstad’s 80 4th quarter penalties so I wanted to dig into those deeper. He called 8 penalties in the 4th quarter of 2 games, week 5 Broncos vs. Raiders and week 14 Chargers vs. Bills. Of his 80 4th quarter penalties, 13 were false starts, 13 were offensive holdings, and 11 were defensive pass interference. He also called 7 delays of game, which are an objectively neutral penalty that shouldn’t be held against him. We’re not assigning blame here, maybe those teams were just undisciplined last season. I just wanted to investigate that 80 number further since it looks like an outlier.
Here’s how the table looks if we eliminate the games column and just divide each total penalties per quarter number by the number of games refereed:
A little bit of re-shuffling here as Shawn Hochuli drops out of the second quarter spotlight.
What was the most frequently called penalty from each ref? Let’s look:
False starts and offensive holdings across the board. What about differences in score differentials and penalties?
Large numbers for 1 possession games, but maybe 1 possession is the most frequent score differential. I’m thinking of that time in the first quarter after a team scores first then the opponents don’t respond right away. What if we narrowed it down to just 4th quarter penalties?
Adrian Hill’s 46 penalties in 1 possession 4th quarter games stands out to me. These are hard to analyze though because how can we tell when a penalty actually happens? Sometimes you can watch any play in slow motion and find a holding call to make if you really wanted to. I just thought this would be a worthwhile study and could snowball into something bigger down the line. I’m interested to hear what you all think about it in the comments below though. Until next time!