MIAMI — It’s not easy to invoke the wrath of Andy Reid, pro football’s most grandfatherly coach. But it is possible, especially during the course of the game.

From 2008-2013, Louis Riddick worked in the Philadelphia Eagles’ front office in multiple roles. His favorite task came Sundays, when he’d sit in a coaches box high above the field, scanning the action and calling out who the opponent would bring into the game on both sides of the ball. The duty was a blessing and a curse.

“Games for me were not always fun, bro,” Riddick, now an analyst at ESPN, told Yahoo Sports. “I didn’t watch it and eat hot dogs. My wife used to say, ‘You’re as tight as the coaches!’

“I remember one time we were playing the Packers, and I’d f—d up a couple of groupings, and it was cold, and they would all have on those big, long overcoats on the sideline, and they would keep them on to the very last minute and then run on the field at the very last minute. It was messing me up.

“And I just remember Andy one time getting on the phone, and he was just like,‘Louis, get your head out of your ass and get the f—g calls in!’ And I was just like, ‘Oooh, boy. OK. OK.’

“That will shake you up a bit.”

View photos Andy Reid has earned a reputation of being on the NFL's top play-calling coaches. (Photo by Wesley Hitt/Getty Images) More

Riddick got a front-row seat to Reid’s coaching genius, which was a hell of a learning experience.

“I knew every call that went in … and I know the kind of things he was looking for, as far as schematic weaknesses and individual player weaknesses,” Riddick said. “Some guys just seem like they’re calling plays for the hell of it … he doesn’t do that.”

Getting to this level of mastery is a laborious process, one that begins with Reid’s legendary play scripts mapping out his first 15 offensive play calls.

And as the Chiefs prepare to face San Francisco in Super Bowl LIV on Sunday, multiple former assistants — including Chicago Bears coach Matt Nagy, Eagles coach Doug Pederson and former Minnesota Vikings head coach Brad Childress — took time with Yahoo Sports this week to explain the importance of Reid’s first 15, how it gets crafted and what they anticipate seeing in Sunday’s Super Bowl.

“In some ways, on the offensive side, he’s kinda like Bill [Belichick] in this way — you better know what your weaknesses are, as much as you know what his strengths are, because he’s gonna find them,” Riddick said. “Otherwise, I promise you at the end of the game, you’ll go ‘Man, he hit every one of our weaknesses.’”

Why the opening play script is important

To a man, all the coaches interviewed for this story agree that the first goal of Reid’s first 15 plays script — which applies to first and second down, and excludes third downs and red-zone plays — is to move the ball down the field and score, all while setting a tone for the rest of the game.

“The game has so many ebbs and flows,” Childress said. “Obviously, it’s important to get your quarterback some easy completions to start with, if there is such a thing. Maybe you’re wanting to get over the top and send a message. Or maybe, because of nerves, you’re just wanting to let your offensive line screw their heels in the ground, and be able to fire off on somebody and run the ball.”

The second purpose is the critical gathering of intel. Even when the Chiefs’ early play-calling goes nowhere (as it has in their past two playoff games), the amount of thought Reid has put into it means that every play Kansas City runs gives it a chance to pick up a defensive tell that can pay off later in the game.

This happens the moment the play clock begins, starting with who defenses put on the field. That’s why Reid needs his assistants to identify them correctly.

“For instance, let’s say it’s a two-tight end, two-wide set,” Childress said. “Are you gonna play nickel against that? People have done that before because they look at [Travis] Kelce like a wide receiver. If they do that, you want to be sure you have some ideas about how to counter that.”

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