It was the play of the day on Wednesday.

It may have been the play of OTAs.

That’s the type of impact No. 1 pick Ryan Shazier continues to have this spring on the South Side.

Backup QB Bruce Gradkowski was the latest to be left shaking his head at the rookie inside linebacker’s explosive athleticism following an interception by Shazier that Gradkowski never saw coming.

“The play you saw him make today was unbelievable,” Gradkowski gushed.

Even to a nine-year NFL veteran.

Shazier’s latest confirmation of the special qualities that overwhelmingly sold the Steelers in their pre-draft preparation resulted from a play Shazier thought he could make all along and one Gradkowski never for an instant considered Shazier capable of making.

“No, I didn’t, I definitely didn’t,” Gradkowski acknowledged. “I thought, ‘OK, let me just lay this over him.’ I saw (wide receiver) Martavis (Bryant) coming in the window. (Shazier) jumped and I still have this snapshot in my head. I’m like, ‘this dude was 90 feet off the ground.’”

Shazier didn’t get quite that high.

But he got high enough to establish that he’s more than just a fast guy at inside linebacker.

“Oh, man,” Gradkowski continued. “I asked him after, ‘What was your vertical coming out?’ He said it was 42 inches. I said, ‘What are you guys eating nowadays?’ What an athlete, he’s fast, he can jump. He’s a young guy willing to learn and grow, a smart kid.

“It’s exciting to see young guys like that.”

Shazier saw his eye-popping interception mostly as a result of his doing what comes naturally.

“We were in a certain coverage; I had a zone-drop,” he explained. “I read the quarterback’s eyes. I knew he thought he was going to be able to get it over me. I just jumped up and did what I can.

“It was a little high but I felt I could get up there.”

It was still just a play made while playing football in shorts.

But ever since the Steelers began doing that Shazier has been getting noticed.

He opened OTAs by lining up next to Lawrence Timmons at inside linebacker with the first-team defense on Day One.

He’s since mixed it up with Maurkice Pouncey in a manner the veteran center characterized as excessive, and paid the price for peeking into the backfield at the wrong time on what became a catch-and-run chunk play by veteran tight end Heath Miller.

As Shazier’s indoctrination continues, the Steelers’ anticipation of what he’ll do when the shoulder pads finally come on is heightened, seemingly on a daily basis.

“A veteran like myself, you never want to see that happen,” Gradkowski said of Shazier’s out-of-nowhere INT. “At the same time I hope we see a lot of that from him this year.

“In a sense I’m kinda mad it happened. In another, it’s good to see young guys making plays.”