ALLEN PARK, Mich. -- The embattled Detroit Lions defense has lost a key piece of the secondary for the season, while coach Dan Campbell is defending second-year defensive coordinator Kelvin Sheppard.
Lions defensive back Avonte Maddox will miss the remainder of the season after suffering a foot injury that requires surgery, Campbell announced Monday.
Campbell, meanwhile, defended Sheppard, whose defense has given up 71 points through the first two weeks of the season.
"I believe in Sheppard. I believe he's an outstanding coach. There's a bump in the road," Campbell said. "I think this staff is outstanding. That defensive staff.
"It's a veteran staff, and I think they're versatile and we've got to coach better -- and they can coach better, I can coach better, but I believe they're the right guys to get this thing done."
This Sunday, the Lions (1-1) host the New York Jets, coached by Aaron Glenn, whom Sheppard succeeded as the Lions' defensive coordinator.
Maddox was hurt during the first half of Thursday night's 41-31 loss to the Buffalo Bills, getting carted off the field and ruled out in the inaugural regular-season game at Highmark Stadium. He went down after a second-quarter collision with teammate Chuck Clark in the end zone and limped off the field next to team trainers before going to the locker room on a cart.
"That hurts a little bit. Maddox is a good player for us. A good solid football player. I hate that for him," Campbell said. "That's the hand we're dealt, and we move forward."
The Lions are also missing starting safeties Brian Branch (Achilles) and Kerby Joseph (knee), who are on the physically unable to perform list and still must miss at least the next two games.
Campbell said they won't return to practice this week, with no clear timetable set for either player to return, but Branch could return sooner than Joseph -- whose chronic knee injury continues to linger.
"I just know we were strengthening the knee, and it wasn't a setback, but there was a little time there where we weren't able to do everything we needed to do and so now, we're back at it," Campbell said of Joseph. "And until we can get the knee to a certain point to where it feels strong, as strong as we can possibly get it and he feels comfortable, we're not gonna put him out there until he's ready."
With Detroit's defense depleted in the secondary, made a move Monday to reinforce the unit. The Lions are signing veteran defensive back Jalen Mills to the practice squad after a workout that also included Jordan Fuller and Mike Edwards, sources told ESPN's Jeremy Fowler. Mills appeared in three games for the Lions last season.
The Lions' defense couldn't stop the Bills, allowing 446 yards and 34 first downs while forcing just two punts. That continues a trend from Week 1 as the Detroit defense has allowed 63 first downs this season, which is tied for the second most all time through two games, per ESPN Research.
"[Lions general manager] Brad [Holmes] has been working on getting some guys in here. We had them work out this morning, just looking for a veteran guy, and then we're looking for some of these safeties that are on other teams right now that are promising young players that we can potentially poach and bring in," Campbell said. "And let them compete."