“Coach Grinch, I think he has a loose screw or something,” said Oklahoma sophomore rush linebacker Ronnie Perkins.

Hey, that’s not a bad thing, and it certainly wasn’t phrased as a negative by Perkins. After a few months of speculating about what first-year defensive coordinator Alex Grinch was going to be like calling the shots in Norman, Thursday afternoon was the first taste for everybody involved.

That first impression? Intense, fiery and an incredibly hands-on approach. Everything that had been said about who Grinch was lived up to the billing, and then some.

This is his defense. He’s setting the tone. It started in January but is about to go to whole ‘nother level with spring football.

You’re either in, or you’re left behind.

“By the way they do things, all of them not forgetting about one person out there,” said junior cornerback Tre Brown about what’s different. “Everyone's hustling to the football. If you ain't, there's consequences. That pulls a trigger in your mind that you better keep rolling. You can't stop out there. You gotta go 100 percent.”

The media only saw the initial part of practice, but Brown wasn’t lying. If a drill or a rep wasn’t run to Grinch’s liking, it was redone until executed correctly. Not afraid to speak up, Grinch asserted himself repeatedly.

It takes a certain breed to be a defensive coordinator, no doubt about that. Grinch running with the defense and his infectious enthusiasm, though, just felt different. It’s all gas for Grinch, the only way he knows.

“I was brought up by Gary Pinkel, Sean McDonnel at New Hampshire, who does a phenomenal job out there,” Grinch said. “But it was ‘coach every snap.’ They put a whistle in your hands to coach so you’re not a bystander. You’re not watching, you’re not a cheerleader. Coaching is a critiquing business, so that’s all I know and that’s all this coaching staff does.”

Following three seasons at Washington State and one season at Ohio State in his most recent stops, Grinch was the man pegged by head coach Lincoln Riley as the one who can turn this defense around. Grinch is making $1.4 million this season, the most for an OU assistant coach ever.

Grinch’s message is simple. This is going to be an effort-based defense. The term “Speed D” was coined by Riley on Wednesday in attempting to give the system a name.

Scheme will come all in due time. These initial moments together are about seeing their sense of urgency every minute of every practice.

“Regardless of the newness, I want to see guys play with some — I say some, quite frankly, a high level — of energy. Guys running around,” Grinch said. “The thing we told them going into it, you can have bad plays. You can’t have a bad day if you play with tremendous effort.

“So what we’re not going to do is say it’s an effort-based defense and all of a sudden you get to spring football and the effort is secondary to scheme. I thought for the most part that was good, which it should be. It should be exciting.

“We’ve done a lot of walk-throughs now. We’ve got just over about 800 snaps of walk-throughs with those ‘x’ number of hours we’re allowed by the NCAA up until this point. So 800 reps of pretend. And believe me, the pads aren’t on yet. It’s still half pretend. But there’s a ball, there’s some moving targets. So some positive, some negative and we’ll continue to work through it.”

Grinch spent the last couple of months doing what he could to establish a relationship with the players. He had individual meetings with each defensive player. Grinch was hoping for an open dialogue that lets the players know the coaches have their backs and for the players to have an open mind.

What’s in the past is in the past. Leave it there. It’s a fresh start, clean slate – take advantage of the opportunities and set high expectations along the way.

There’s a defensive standard OU fans knew in the past. It has been absent during the last couple of seasons. If it’s going to change, it starts with Grinch. He knows that. He showed that Thursday.

“He’s hype guy. He’s vocal. I like people like that,” Perkins said. “He gives you energy. When he’s hyping you up and bringing you energy, you want to go out and make a play for him and get hype with him again. He’s brings a lot of energy to it and I saw that today. I liked it.”