INDIANAPOLIS -- If Indianapolis Colts coach Frank Reich was going to lose anybody off his staff to be a head coach this offseason, the thought was it would be defensive coordinator Matt Eberflus, not offensive coordinator Nick Sirianni.

Sirianni is now the head coach of the Philadelphia Eagles and Eberflus remains with the Colts.

Eberflus, who interviewed for the Houston Texans job, staying in Indianapolis is a good thing for the organization because he’s brought an aggressive, fast and play-through-the-whistle approach. It has helped transformed a defense that struggled for many years when Chuck Pagano coached the Colts.

That’s not too bad for a coach who wasn’t handpicked by Reich when he was hired in the winter of 2018.

"I think the world of Matt as a coach, as a person, as a defensive coordinator -- that we can ... have the continuity and just keep building, growing and adapting the system to our players," Reich said earlier this year. "I’ve just seen Flus continue to grow and develop in that role as well, really connecting with players, making a conscious effort every week to put our players in the best position possible.

"He is extremely intelligent, very focused in on a vision for how he sees the defense executing and where we want to be as a defense.”

The 2021 offseason was about adding pieces on defense, especially with the departures of defensive ends Justin Houston and Denico Autry and linebacker Anthony Walker.

The Colts used their first two draft picks on edge rushers Kwity Paye and Dayo Odeyingbo to join the unit’s anchors in linebacker Darius Leonard and defensive lineman DeForest Buckner. The additions have given Eberflus the type of depth he’s “never” had during his first three seasons with the Colts.

“They’ve done a great job of building depth here,” Eberflus said. “The competition is all the way through the depth chart, which is outstanding and we’re just looking for it to play out. It just has to play out the way it should play out. The guys that are producing on the field, those are the guys that play. It’s an exciting thing.”

Playing for Eberflus can be a challenge if you don't fit the style he prefers. Players like defensive lineman Tarell Basham, cornerback Quincy Wilson and defensive end Ben Banogu have struggled to meet the expectations necessary to get snaps on the field. Basham and Wilson are no longer with the Colts and the clock is ticking on Banogu.

What entices so many players about Eberflus’ scheme is it’s not robotic. His nonstop, play-through-the-whistle and all 11 players pursuing the ball approach allows for them to “play free” without being limited.

“Coach Flus came in and was nothing short of spectacular,” Walker, who is now with the Cleveland Browns, said at the end of last season. “The main thing is the constant message of running to the ball and takeaways. Harping on it with us and never changing that message. That’s the biggest thing from being a player for so long, some coaches come in and say we’re going to hustle, take the ball away and all that. But then you won’t hear about it until the next year. But with Flus, you hear that everyday. His constant message.”

Buckner added, “What’s not to love about that if you’re a player playing for Flus?”

For as much as implementing the right scheme to stop an Aaron Rodgers in the air or Derrick Henry on the ground is important, Eberflus has helped Leonard become one of the NFL's premier defensive players and made Buckner’s transition to the Colts smooth by also keeping it simple by emphasizing speed, hustle and effort.

And Eberflus lets each player know what is expected when they arrive and reiterates the message daily. He has a "H.I.T.S." principle that has a meaning behind each letter:

• H: Hustle

• I: Intensity

• T: Taking the ball away

• S: Situationally smart

“That’s the pillars we’ve had since we’ve been here,” Eberflus said. “It’s the H.I.T.S. principle and we talk about it every single day. It’s in our defensive room, it’s all over the place. That’s the No. 1 thing because it’s the No. 1 thing.”

The Colts gave up the eighth-fewest yards and were fifth in the league in turnovers forced last season.

“The way he’s taught us about passion, intensity and taking the ball away and being situationally smart, he’s ingrained that in us," cornerback Kenny Moore said. "We love coach Flus.”

And it gets better. Eberflus also employs a "loaf" system.

The staff reviews film and charts to see how hard a player works on the field. They want their defensive players going full speed from the snap of the ball until after the whistle is blown. It’s never a good thing to have a high number of loafs, because it means the player isn’t putting in the type of effort coaches expect. And it’s embarrassing to be called out in front of teammates about having a loaf.

Tampa Bay coaches Tony Dungy, Monte Kiffin and Rod Marinelli taught Eberflus the loafing system.

How Eberflus goes about things with his stat tracking and some of the philosophies he uses may seem quirky to some, but it’s embraced in the organization.

“I’ve never seen anything where there is an accountability on loafs at the level that we have it here,” Reich said. “What makes it work is the players believe it and see it, and we know there is tangible proof that it works and that it matters.

“Every week someone on the opposing coaching staff is going to go out of their way to walk over to me and say, ‘Man, I really respect how hard your defense plays, how much they run to the ball.’ I think that’s a testament to our players, but I also think to Flus and the defensive coaching staff for that accountability. That it’s a group thing together.”