The Packers defense has taken a big hit with the loss of one of the few players they could rely on to give a big hit. Coach Mike McCarthy confirmed the bad news Saturday evening: ILB Desmond Bishop will need to have hamstring surgery and “his season is in jeopardy.”

Bishop was badly injured in Thursday’s preseason opener at San Diego when a Chargers player landed on top of his hyperextended right leg. A physical leader on defense who led the team in tackles (115) and was second in sacks (5) and forced fumbles (2), Bishop leaves a large void in the middle of the Packers’ 3-4 defense, which was a notoriously weak-tackling and poor-rushing unit last year. 

McCarthy said it’s never a good time to lose a player like Bishop, as dynamic as he is, and admitted, “I feel terrible for Desmond.”

He added that Bishop also had suffered a knee sprain. He said the team will explore the option of utilizing the new NFL injury rule that, if it is passed by the Players Association, could allow Bishop to return later in the season as long as he stays on the 53-man roster.

Second-year ILB D.J. Smith, who had 27 tackles and an INT in three starts replacing an injured Bishop last season, will step in and is “ready to go," McCarthy said. "He played well when he was needed last year.”

In other not-so-great injury news, McCarthy said CB Davon House will be out two-to-three weeks with the shoulder injury he suffered at San Diego. McCarthy called the injury a subluxation, essentially a dislocation, which is what House described when he said his shoulder popped out on the special teams play. McCarthy said House is “very eager to get after rehabbing” and, after three weeks, the team would decide if he has to wear a protective harness or possibly undergo surgery.

House was playing well in camp and had an excellent game against the Chargers. He was the leading candidate for the No. 2 CB job, so his loss is also quite damaging to the defense. McCarthy said embattled third-year nickelback Sam Shields is “coming along,” and rookie CB Casey Hayward graded out well in the game at San Diego. Along with veteran Jarrett Bush, who’s physical but limited in coverage, one of those players will get the next shot to be the No. 2 CB.

RB stable bare: James Starks has turf toe and is out “week-to-week,” McCarthy said Saturday. The incumbent starter, Starks had been average in camp and had a poor performance against the Chargers. But he’s atop the depth chart and, with third-stringer Brandon Saine (hamstring) not set to return for about a week and backup Alex Green on a “snap count” as he continues to recover from last season’s ACL tear, it’s slim pickings in the Packers backfield. 

That could explain why veteran Cedric Benson was reportedly in Green Bay on Friday and close to signing a deal, according to multiple sources. McCarthy, unsurprisingly, did not comment on Benson since no transaction had occurred.

Wells a fit on OL: The Packers signed OL Reggie Wells last week to shore up their offensive line, which is banged-up and lacks pro-caliber backups. Wells (6-4, 318) has played in 117 career games with 91 starts (79 at LG, 10 at RT and two at LT), mostly for the Arizona Cardinals. “Reggie Wells fits our profile,” McCarthy said Saturday, who added the veteran will be looked at at guard and tackle. 

Wells said he’s excited to be in Green Bay. “I came in some years ago when I was a restricted free agent and really enjoyed my trip,” he said. “Still knew some of the coaches and things like that. I’m just excited to get back at it and excited to have another opportunity. I never was in the retirement mode, so to speak. [I was] just working out and staying active, and preparing myself. There were other teams that called before this. It was just a matter of trying to find the best opportunity from there.”

Notable injury news: A total of 21 players did not participate in practice Saturday due to injury. McCarthy said LT Marshall Newhouse (concussion), out a week, is still going through the head-injury protocol. The coach said TE Jermichael Finley (quad) “will be pressed to make it” for Thursday night’s preseason game against the Browns. Rookie DE Jerel Worthy has a shoulder injury that should sideline him only a couple of days.

Follow Packers reporter James Carlton on Twitter @CBSSportsNFLGB and @jimmycarlton88.