The NFL Live crew is on board with new replay rules, but it has some concerns over officiating ruining the flow of the game. (2:00)

The NFL maintains a thick wall around its referees, limiting their public exposure to occasional pool reports and once-per-year training camp visits with reporters. Only when they retire can officials speak freely about the underworld of the league's 33rd team.

So as the regular season approaches, I jumped at the chance to chat at length with John Parry, who stepped away from 19 years as an NFL official to join ESPN in April as an officiating analyst. He'll appear weekly on Monday Night Football, explaining and judging the most significant calls of the game.

Parry offered his opinion of senior vice president of officiating Al Riveron, expressed dismay at the lack of training available to current officials and explained how he pushed back at perceptions of favoritism. But most fascinating to me is his description of the "artistry" of officiating and how it affects the frequency of flags thrown, a practice that has produced a seemingly impossible statistical outcome in recent years. We'll start there.

Note: Our conversation has been edited for clarity and flow.

Jump ahead in the conversation to:

Game flow | Preventive officiating

Perceived favoritism | Rams' non-call

Al Riveron | Referee training program

Kevin Seifert: I've been called a nerd, and maybe it's true, but one of the most fascinating things to me about NFL officiating is that there have been nearly the same number of flags thrown in each of the past five years. The numbers are so close, it's hard to imagine they are organic:

15.87 per game in 2018

15.80 in 2017

15.82 in 2016

16.37 in 2015

16.03 in 2014

How could that be? NFL players turn over at a rate of 30% or so per season. Every year there are at least five or six new head coaches. Officials retire and are swapped out. How do all of those things change, but the flag totals don't?

John Parry: They're not managed at all. I never went into a game thinking, 'I've got to hit 12 flags.' But you do have this idea that in a three-hour football game, there probably will be between 10-15 fouls. So it does play in your mind. And I will tell you that when you're in a game with two teams that aren't as disciplined as they should be, and you start to get into that range of 17, 18, 19, mentally you do start to ask yourself, 'Are we calling this game too technical?'

You might bring the crew together during the game and say, 'Hey guys, we're putting the flag down a lot. Let's make sure for the rest of the game that what we're calling is big. It just seems that every fourth or fifth play, I'm making an announcement.'

Seifert: So in a way you're trying to keep the flags within a range.

Parry: There is an art to officiating. You have a three-hour window where the canvas is created, and you're painting hopefully a masterpiece of officiating. So you do think about it. Based on the flow of the game, or how the game is being played, the artistry in great officiating is determining when I will insert myself. There are definitely times when you go to an offensive lineman and say, 'It's a long drive, I get that you're winded. But you've got to get your hands inside when you're blocking. You're challenging me and eventually, if you continue with this technique, you'll force me to throw.' And you'll find that players do work with you. We call that 'preventive officiating.'

Seifert: It's basically warning players who are committing fouls to stop it, right?

Parry: Yeah, you're working with a player to eliminate having to call a foul. You do it all game long, on both sides of the ball. There is a lot of conversation from officials and players and coaches to try to get the best entertainment value for the fan.

John Parry was an NFL official for 19 years before joining ESPN as a rules analyst. Jeffrey Brown/Icon Sportswire

Seifert: And the NFL is fine with that? Don't they grade you for the accuracy of your calls and non-calls?

Parry: That's the artwork of it. We file game reports after every game, so I may put on my game report that in the first quarter, at the 10:20 mark, the left tackle probably had a hold, but I chose not to throw and instead communicated with the player. And then, it never appeared again. The league wants to know if you saw it and what your ruling was. It's when we don't see things we should call that it becomes a problem. Most of the time they support preventive officiating.

Seifert: Without that context, I would imagine that fans, reporters or maybe even coaches will see that and think you either missed a call, are inconsistent or, worse, trying to help one of the teams win -- rather than just avoiding a bogged-down game. Sometimes people assume the worst. I know there was concern, both from fans in New Orleans and even some people within the league, that four officials who live in Southern California worked the NFC Championship Game. As you might have heard, the Los Angeles Rams defeated the New Orleans Saints in a game that included one of the worst missed calls, in favor of the Rams, in NFL playoff history.

Parry: Here's the simplistic answer to that: Every week, every official is dissected and evaluated by the league office. And there's a grade for every game. You have 17 referees whose goal is to work the Super Bowl. You have 17 down judges who are trying to get to the Super Bowl. We're competing to get that honor. To get there, you can't really have more than five mistakes total over the course of 17 weeks.

So as a referee, my goal is accuracy in a three-hour game over anybody who might say I'm partial to Drew Brees, for instance, because we both went to Purdue. It just doesn't happen.

Seifert: Really? Five mistakes is all you can have?

Parry: As I'm talking to you, I'm sitting in my office at home. I'm looking at three posters on the wall: Super Bowl XLI, Super Bowl XLVI and Super Bowl LIII. Those are the three I worked. I know the type of years that I had to get those three posters. I was either 98% or 99% accurate in those years. You get three hours of football and 15 games per year, so that's 45 hours to determine if you get to February.

"To get there, you can't really have more than five mistakes total over the course of 17 weeks," says Parry of earning the chance to work the Super Bowl. Dale Zanine-USA TODAY Sports

Seifert: So that wouldn't leave much room to intentionally make bad calls and change the outcome of a game. I get it. But how do you explain two officials looking at the contact that occurred in the NFC Championship Game and deciding not to throw a flag? (Rams cornerback Nickell Robey-Coleman made clear contact with Saints receiver Tommylee Lewis before the ball arrived.) Their playoff assignments were already set.

Parry: I think one of the things fans don't understand is that an official never starts and ends with the same player. So depending on where the bodies go, what the formation is, what the down and distance is, that dictates where an official starts looking and then where they should move their eyes to next. It's a progression.

When you look at that play -- and like everybody, I've looked at this thing 200 times -- it's a four-second play. In the last two seconds, three officials walk through multiple progressions and then move their eyes toward the area of contact. They see the contact. There's no doubt they saw it. But their eyes probably got there a half-second late. Is the ball in front of the receiver? On top of him? Already past? They had to make a judgment in less than one second.

Sometimes we look at the replay and say, 'Good Lord, how does that guy miss it?' Well, if he's coming off another progression, he doesn't get there quite early enough. He doesn't see all the action. And we're taught every year not to guess. We need to see the whole action and rule on the whole action. When we don't, we lean toward not calling anything.

Seifert: Al Riveron certainly took his share of the blame for that call, fair or otherwise, too.

Parry: Last year, I was one of the 24 officials who participated in the full-time game official program. That meant I had an opportunity to go to New York every other week from Wednesday through Friday and work in the Command Center. I had no idea how busy and how stretched and pulled from so many positions Al Riveron is. We would be trying to evaluate and do the work of the week, and suddenly Mike Tomlin is calling. So Al goes and talks to Tomlin for a while, then he comes back and we're back to film, and then we're interrupted because ESPN has a question about the Monday night game regarding an extension of a timeout, or they want to use a new camera.

It's hard. I like Al. Al is an officials' official. He always supports his people. But I think the NFL has put too much on Al Riveron's plate. The NFL is asking one guy to manage more than 500 people, in an environment where 50% of the league is going to be unhappy every week.

Seifert: That sounds like a structure set up just to survive, not really to innovate or get better. How can the NFL fix that?

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Parry: The position has grown to the point where the department either needs to grow or he needs to have people to delegate to. I would never use the term "undervalue" when you think of how the NFL views officiating, but I think they have to recognize how important it is.

Do they have the right people? Do they have enough people? Can they think outside the box and create better systems and training and recruitment? Seven of the 17 referees have retired in the past two years. Is the recruiting program adequate? There are so many wheels you could look at for improvement, but the league is asking Al to handle all of that, and it's too much.

Seifert: So I'm guessing you wouldn't consider the NFL to have a robust training and recruitment program in place right now...

Parry: When I first entered the league, I had a mentor who would work with me on film work and help me evaluate each decision, where I was standing, the calls I made ... like a big brother. They put their arm around you for a full season and you communicated constantly. The league went away from the mentoring program, and for a period of time we had trainers, basically retired officials who helped. And they were very good.

But right now, I'm almost embarrassed to tell you that there are only two trainers for all of the officials, and they put out training tapes. So the only training anyone is receiving is those weekly tapes. If it were me, I would expand that training and education for officiating so much.

Seifert: That lack of training is especially concerning when you look at the backgrounds of the new officials that are hired each year. Some of them are pretty young.

Parry: One of the areas that does concern me is the speed we're moving people up to the NFL. There is something to be said for cutting your teeth and working each level. I did five years in the Big 10, five years in Arena Football, and in total it was an 18-year process to get to the NFL. That's where you learn and grow. You can't work four, five, six, seven years of football and come to the NFL and be successful.

It's just hard to prepare for. I started at the grassroots, from the lowest levels through high school, and I was a pretty good line judge and side judge in the Big 10. It still took me three or four years to adapt to the speed and the skill set of 22 NFL players on the field at the same time. It's hard.

Seifert: To me, the best news is that we have a growing legion of experts with public access who can assess these issues with context, and in real time, on game broadcasts and highlight shows. I've found that half the complaints I see about NFL officiating come from people who either don't know the rules, haven't been taught officiating mechanics or have an overriding emotional stake in the outcome of a game.

Parry: We're not going to agree with every call, but credible discussion of it is good for the conversation at large.

Tune in to Monday Night Football all season long for more officiating and penalty analysis from John Parry.