The Legion of Boom took a double whammy last Thursday, losing both Richard Sherman and Kam Chancellor.

Sherman is out for the season, recovering from surgery on his Achilles and looking toward a return next spring. Chancellor apparently could be following him.

It sounds like the strong safety is out this week with the stinger (i.e., nerve issue) suffered against Arizona, and rumors are flying that he could be out for the season as well.

Pete Carroll said he was still undergoing tests this week and his prognosis was unclear. It sounds like his injury might not be as serious as the one that sidelined Cliff Avril earlier this season and has Avril considering his football future. But the loss of Chancellor would be another tough blow — making him the third starter gone from Seattle’s star-studded defense.

As two LOBers leave, one returns: Earl Thomas will be back from the hamstring injury that cost him the last two games. Bradley McDougald, who has been very steady in Thomas’ place, will slide over to strong safety now. And Sherman will be replaced by Jeremy Lane and newly re-signed Legion of Boom original Byron Maxwell.

The other big injury is to left tackle Duane Brown, who will be a game-time decision due to an ankle injury suffered at Arizona.

The Seahawks have a host of other injury issues coming out of last week. Here’s a look at the medical status of each position:

QB: The NFL is still investigating whether the Seahawks violated concussion protocol with Russell Wilson, who initially declined to be evaluated. After missing one play running around on the sideline, he finished the drive and then underwent the test after that series. He had no symptoms and was totally fine, aside from a very sore jaw that apparently had him off solid foods over the weekend, but the NFL might end up fining Seattle for the snafu. The typical first-offense fine is $150,000 — which for Paul Allen is like $2 to you and me. This is not a story — unless the NFL decides to steal a draft pick from Seattle as (overly harsh) punishment.

RB: C.J. Prosise (ankle) was finally placed on IR — a move that seemed destined to occur since the beginning of time. The Hawks now have three backs on IR, including Chris Carson and Tre Madden. Prosise will be replaced by Mike Davis, the preseason star many fans had been calling for. Eddie Lacy (groin) also is expected to practice after missing the Arizona game. Thomas Rawls figures to lead the charge vs. Atlanta, but many expect Davis to push his way into the mix quickly. Carroll said he considers it a race to see whether Carson or Prosise gets back first this season, but Carson is unlikely to return from his leg fracture (and Carroll kind of admits it).

WR: The Hawks should be OK here. In Arizona, Doug Baldwin played with a hip injury suffered in pregame warmups and Paul Richardson had a tight groin. But both came up big. Richardson hauled in a 43-yard pass that set up a field goal and a 15-7 lead, and Baldwin was on the other end of Wilson’s magical scramble that resulted in a 54-yard pass play and the clinching TD. The query of the day: With the Browns waiving Kasen Williams, would the Hawks be interested in adding him to the practice squad again if he clears waivers?

TE: This position escaped unscathed and looks to be getting stronger, with the Seahawks finally figuring out how to use Jimmy Graham in the red zone. He caught two short TD passes against Arizona and has six TD catches in the last five games. Graham is dealing with a knee issue, but it has not stopped him from scoring touchdowns.

OL: Brown will be a game-time decision, Carroll said. And the left tackle said he is taking it day by day. If he can’t make it back, Matt Tobin would become their third left tackle this season (fourth if you count George Fant, who was lost for the year in preseason). The Hawks put Rees Odhiambo (hands) on IR last week. If Brown is out longer than a week and Tobin has a tough time vs. the Falcons, it also seems possible that Luke Joeckel might move over. Coming back from knee surgery, he is expected to practice this week. Once Joeckel is back, Ethan Pocic will battle the struggling Oday Aboushi at right guard, Tom Cable said.

DL: Maybe the best news comes at this position. Marcus Smith (concussion) and Frank Clark (thigh) look like they will be good to go — Smith missed last week and Clark was injured late in a collision with Sheldon Richardson. Jarran Reed (hamstring) also could make it back after leaving early vs. Arizona; Carroll said he is a game-time decision. Richardson (oblique) and Michael Bennett (heel) have been playing injured, but the depth is pretty darn good — with 11 guys on this unit. Dion Jordan is coming off a great first game, Dwight Freeney and Nazair Jones have been stellar and Branden Jackson, Garrison Smith and Quinton Jefferson have been solid in reserve.

LB: Michael Wilhoite (calf) is the only concern here. Terence Garvin (shoulder) practiced Thursday. Bobby Wagner and K.J. Wright continue to be iron men, playing stellar football.

CB: With 2016 starters Sherman and DeShawn Shead out, it is up to rookie Shaquill Griffin and Legion of Boom vets Lane and Maxwell, plus excellent slot corner Justin Coleman and special-teams dynamo Neiko Thorpe, to lead the way. Lane (thigh), Maxwell (hamstring) and Griffin (shoulder) are coming back from their own nicks and bruises, but all should be ready to roll. As for Shead (ACL), Carroll said, “DeShawn is really close. We are trying to get him over the hump. He’s really frustrated by it ’cause he’s worked so hard. He’s in great shape, but he just isn’t quite fully functioning the way we need him be to fully cut him loose. He’s right on the edge of it. We’ll keep cheerleading for him because he’s such an extraordinary kid.” The Hawks apparently can activate him at any time, with no deadline.

S: If it seems like Thomas and Chancellor barely play together anymore, that’s because they don’t. They played just 11 games together in 2015 and seven last season — and could end up with just seven this year. Chancellor is a tough loss because he played his best game of the season in Arizona (forced fumble, safety and 10 tackles) and seemed like he was turning it on for the second half, like he usually does. We all knew McDougald would be needed at some point this season, but now it looks like he could be the strong safety for the rest of the year. They have to hope Thomas stays healthy the rest of the way, or we will end up seeing rookie Delano Hill at strong safety.