The USFL has a 'Jeff Fisher Rule.' It's an example of spring football league adjusting on fly.

Mike Pereira wrote the USFL rulebook, so he's partial to the previously amended version. That doesn't stop his phone from ringing with suggestions.

And that's the beauty of a spring football league, Pereira said – changes can be made on the fly, even between Week 4 and Week 5.

"Honestly, we are a spring league and it is a new league – making the rules, 98% of the rules are NFL. When you’re making some changes like this, there's no data," Pereira told USA TODAY Sports last week. "Therefore it’s the kind of league where it can be four weeks into the season and you make the change."

For example, the Jeff Fisher Rule. The former Tennessee Titans and St. Louis/Los Angeles Rams head coach, currently leading the Michigan Panthers, called a timeout because he wanted to change from a 1-point attempt following a touchdown to a 2-point try.

The rules stated that the Panthers had to go for one and that he couldn't change the decision, even with the timeout. Fisher pleaded his case during the game and again to Pereira on the phone.

"And he said 'Well who wrote that rule?' and I said, 'Well I did.' And he said 'Well can I propose a change?' I mean, it does make sense to me," Pereira said.

Fisher wrote up a proposal that said coaches can change their extra-point selections if a timeout is used. Pereira assembled an ad hoc committee of Fox and USFL executives and read it aloud.

"And the next thing you know, over a Zoom call, everybody raises their hands and it’s passed," Pereira said. "I like that. I think that’s the way it should be."

That rule was passed at 4 o'clock on a Thursday and the Panthers played the next night with the option at Fisher's disposal, if he so chose.

It's one of a few changes the USFL has made as it enters Week 6 this weekend.

To speed up games, the USFL thought a 35-second play clock would be beneficial. It backfired instead. There are a lot more plays because of less time between them, and games were blowing past the three-hour mark.

After Week 3, executives decided to wind the clock after incompletions in the first and third quarter, Pereira said. Three of four games the next weekend took less than three hours.

He added: "I’m sure we’ll be open-minded like this going forward."

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How can USFL rules impact the NFL?

The NFL would have a much more difficult time making a rule change midseason. "Points of emphasis" are rarely officiated the way the NFL's Competition Committee intended, and those penalties – such as sacks in which defenders put their full weight on the quarterback – become ignored.

"I think the other thing that people are looking at is how involved the replay center is and I do think that’s made a difference," Pereira said.

Not only in transparency because viewers can hear the reviews, a broadcasting tactic that XFL 2020 found success with, but also that USFL officials can review personal fouls such as a 15-yard roughing the passer or facemask.

"That’s been a positive change," Pereira said.

One rule specifically is being monitored by the NFL, in an effort to improve player safety on punts, Pereira said. In the USFL, "gunners" – players on the kicking team that lead coverage efforts – aren't allowed to line up outside the numbers and the receiving team can't double-team the gunner until the ball is kicked.

The NFL has been paying attention to other data, he said. Additionally, 33 of the USFL's 35 referees are in the NFL's Officiating Development Program.

Where are the 3-point PATs in the USFL?

The 3-point try, from the 10-yard line, was meant to mean a 17-point game in the fourth quarter was still a two-possession game. Only one 3-point PAT has been attempted, though, when Philadelphia Stars running back Maurice Alexander caught a short pass from Bryan Scott and darted into the end zone on April 23, extending a four-point lead to seven.

Pereira said it was the highlight of the season for him so far.

"I was just like on the edge of my chair going, 'Come on, make it! Make it!' " Pereira said.

As for why the 3-pointer hasn't caught on, Pereira said the coaches must have determined the 10-yard attempt isn't worth the extra point or two.

Follow Chris Bumbaca on Twitter @BOOMbaca.

This article originally appeared on USA TODAY: Mike Pereira explains how Jeff Fisher impacted USFL rules