ALLEN PARK -- Glover Quin had started 122 straight games and played every snap for 23 in a row at a position that helps define Teryl Austin's two high-safety approach.

Then Sunday happened, with a big hit leaving him down on the turf for minutes in a loss to the New Orleans Saints. A trip to the locker room ensued. And now the questions have to be asked.

The Detroit Lions are in their bye week, a much-needed break from the injuries that are piling up on their best players, from Matthew Stafford to TJ Lang to Golden Tate to Quin. Health issues are a regular part of playing in the NFL these days, and the Lions are no stranger.

Playing without Quin, though, would be something new.

It's hard to know how far out Quin is from playing again, in part because that's how the Lions operate and also because the concussion protocol can be so unpredictable. It has five stages for returning to play, and certain ones last differently for every player. Some clear it in time for a game the very next week. Others, like Green Bay Packers cornerback Sam Shields last season, can miss months on end and then see their career never start up again.

The Lions have no need yet to think anything drastic about Quin, but the fact that they have to think at all about what's behind him is fairly new. At 31 years old, he'd become their iron man, the stabilizing force at the back end of a 4-3 defense that has worked on getting younger. As the free safety, Quin handles the role of commanding a deep secondary but also of providing a last line of defense for a scheme built around preventing the deep pass.

His backups are fairly green players with wide ranges of skills. At 5 feet 10 inches and 192 pounds, Charles Washington is more of the traditional free-ranger, with speed that gives him regular reps on special teams. As a second-year undrafted player, he only has six career games and zero starts, but he was the man called in for Quin last Sunday.

That's in part because second-year Miles Killebrew had other responsibilities at hand, such as filling in for a briefly injured Tavon Wilson. And at 6 feet 2 inches and 222 pounds, he's a far more diverse skill set that needs more of a specific game plan than a call off the bench in the heat of a game.

Lions coaches have the time to do that with a bye week prior to hosting the Pittsburgh Steelers on Sunday Night Football. They can tinker with a player in Killebrew that Quin theorizes they drafted with him in mind. Both are balanced skill sets drafted a pick apart in the fourth round, developmental pieces who had the chance to do a little of everything.

"I think in this defense, that position, safety, has to be able to play more than one area on the field," Killebrew said. "What might be a safety here might not be a safety somewhere else."

For deep dive into the path Killebrew took in Las Vegas to become a hybrid player and how a week of tragedy back home challenged everything he had, head here.

No Quin replacement would do all of what he does, of course, or as well. The Lions could decide to attack it with more three-safety sets, using both Killebrew and Washington in addition to Wilson to address a problem with numbers.

What they prefer, obviously, is to not have to worry much about it. Two weeks is a good amount of time to let a player try to clear the protocol. Quin's most important asset is his mind, but he's also spent large amounts of time installing it onto the younger players for whenever their time eventually comes.

Detroit will find out in a week how close it is to that point.