Following the Iowa football team’s final spring practice on April 23, senior defensive back Terry Roberts began his conversation with reporters with quite a soundbite.

“This defense can be the best in the nation,” Roberts said.

This may not seem like such a strong statement given the Hawkeyes’ recent success on defense. Last season, Iowa led the country with 25 interceptions and ranked 17th nationally in total defense.

The Hawkeyes gave up an average of 17.3 points per game in the regular season. After two postseason games, the Hawkeyes ranked fifth in the Big Ten with 19.2 points allowed per game.

All that success, however, came with defensive backs Jack Koerner and Matt Hankins, linebacker Dane Belton, and defensive lineman Zach VanValkenberg on the field for the majority of snaps.

Each of those players joined NFL teams last week.

Belton was drafted by the New York Giants in the fourth round, and Koerner, Hankins, and VanValkenberg were picked up as undrafted free agents by the New Orleans Saints, Atlanta Falcons, and Las Vegas Raiders, respectively.

But in the last few years, Iowa’s defense has consistently developed NFL-level players — Amani Hooker, Michah Hyde, Geno Stone, and Josey Jewel — and remains near the top of many defensive categories both in the Big Ten and in the country.

Roberts said that a large part of the Iowa defense’s sustained success can be attributed to its signal-caller: defensive coordinator Phil Parker.

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“Coach Parker, he’s the best defensive coordinator in this country right now,” Roberts said. “He prepares us day-in and day-out. Mentally, physically, all that. He tells us to strive to be perfect even though no one in this world is going to be perfect, no one can be perfect. But when you strive to be perfect, then that’s when you can become the best player you can be.”

Roberts said Parker is not only focused on getting his players’ bodies ready to play. Parker is also intent on developing his athletes’ minds, Roberts said, to put them in the right place on the field.

“I think it’s all aspects,” Roberts said of Parker’s coaching. “I think it’s mental and physical, but it’s more mental. Football is more mental than physical because if you don’t know what you’re doing mentally then you can’t be out there. You’re not gonna be able to make the plays. He over-prepares us so that we’re prepared for anything that comes.”

Parker told the media during an April 6 press conference that his philosophy for putting the best defense he can on the field each week comes down to two simple principles: evaluation and fairness.

“You got to play the best guy that’s gonna help your team win,” Parker said. “If I don’t do that, I’m not fair to everybody else … How consistent are you? The guys that usually dictate who’s playing, it’s the guys, the players … You make less mistakes than the other guy, simple.

“Why do you think I want to play the good guys? The guys can play well, why? Because if we don’t win, what happens? Unemployment line.”