Santa Clara, Calif. — Quandre Diggs sat in his locker, a man found guilty by officials, but confident of his innocence.

The physical Detroit Lions cornerback was punished for the physicality on Sunday, flagged for holding San Francisco 49ers tight end George Kittle, a man who has seven inches and 50 pounds on the Lions defense back.

The infraction, which occurred away from the direction 49ers quarterback Jimmy Garoppolo threw the ball, ended up negating rookie safety Tracy Walker’s interception in the game's final minutes, and cost the Lions an opportunity to put the finishing touches on a 17-point fourth-quarter comeback in what ultimately ended up a 30-27 loss on Sunday.

“Awful,” Diggs said. “That's what I thought of it. So you take it, man up, and get ready for next week. But I just ... I'm going to look at it again, but I have a pretty good memory. And I know.”

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Diggs said the official who would normally be responsible for monitoring for holding on the play claimed he didn’t throw the flag, leaving the cornerback with no explanation for why he was penalized.

“Frustrating because I didn't think it was the right call,” Diggs said. “I don't think you make that call at the end of the game away from the ball, in clutch time. You don't make that call. And, you know, I'm not going to get fined for it, but I'm not happy with the call.

“I didn't know you could hold when you jam somebody," Diggs said. "So, like I say man, go back to work, just try to perfect my craft and watch the film.”

It was the rough ending on a rough night for Diggs, who also lost his footing on a 66-yard touchdown run in the third quarter, wiping out teammate Teez Tabor along with Detroit's last line of defense to limit the damage on the play.

“We can't have those plays, and we all got to clean that up,” he said. “The front, the back end — it's my responsibility to get that guy down, and I didn't. Just didn't make the play I've been known to make. I'll take that. I guess that comes with the recognition. I don't have no problem taking that. I have no problem being in the fire. I've been through the fire, man.”

Diggs signed an extension earlier this month, a three-year pact worth $18 million. He’s been one of the team’s most dependable defenders the past two seasons. In the season-opening loss to the Jets on Monday, he was one of the few bright spots, recording a pick-six on the game’s first play.

jdrogers@detroitnews.com

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