When rookie safety Juan Thornhill went down in Kansas City’s Week 17 win against Los Angeles, Andy Reid and Steve Spagnuolo had just a matter of minutes to formulate a backup plan.

Two weeks later and down their 2019 second-round pick after a torn ACL placed Thornhill on injured reserve, the Chiefs are considering all options heading into Sunday’s AFC Divisional Round matchup with the Houston Texans at Arrowhead Stadium.

In a scheme that regularly played just two safeties, safety Tyrann Mathieu could be paired with Daniel Sorensen, his secondary mate with two interceptions this year. The team has also taken the time to play Kendall Fuller in a safety role for the latter part of the season.

With Spagnuolo’s preference to have as many versatile safeties on the field as possible, all three are already on the field fairly often. With a healthy secondary, all four players saw at least 54 snaps. It was Armani Watts who saw the largest jump in field time, playing 48 snaps to account for more than half his season total in one game.

“I just feel like I’m ready to step in whenever,” Watts told reporters in the locker room this week. “We prepare all week like everybody is ready to step in whenever needed, so that’s the big thing about this team is being prepared no matter what the situation. Anything can happen.”

Watts, the 5-foot-11, 205-pounder is a second-year pro out of Texas A&M, coming to the team as a fourth-round pick in 2018. He played at least 20% of the snaps in three of the first five weeks last year before a season-ending groin injury.

He saw the field in just five defensive snaps the first 12 games of the year but has carved out a role on special teams, totaling 280 — fourth most on the team. He now is likely to be leaned on for a defense that has been the best in the NFL since Week 11.

“That’s the way it works,” special teams coordinator Dave Toub said Thursday. “Guys move up. He was a four-phase special teams guy, and now he’s playing a lot of defense. So, you have to make up for it in other ways. Other guys will have to pick up.

“It’s going to help him (Watts) with confidence on defense. It’s not like he hasn’t been practicing over there, either. All this time is really going to help him.”

Watts finished the season with 74 defensive snaps and an effective showing in the finale. Playing a deep coverage role alongside Fuller, with Mathieu and Sorensen often hovering the line of scrimmage, Watts recorded three tackles against the Chargers.

“What you see with the guys, particularly linebackers and safeties that play on special teams when they’re young, then you see them develop, are angles and speed of the game,” head coach Andy Reid said. “Angles to the ball. They get accustomed to the speed of the game and playing in space. I would tell you that’s what he has learned through his special teams play.”

Watts finished this season with five tackles, a sack, two quarterback hits and a pass defense. He made an impact earlier in the season by sniffing a fake punt at Denver.

“I thought he did a nice job filling in two weeks ago, a week and a half ago,” defensive coordinator Steve Spagnuolo said. “For one, it was unfortunate what happened to Juan, but that’s what guys are expected to do. When somebody gets hurt, you got to step in. First, you need to know what you’re doing. I think the assistant coaches have done a great job with that.”

Brandon Zenner can be reached

at brandon.zenner@newspressnow.com.

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