FLOWERY BRANCH, Ga. (AP) -- Another week brought another series of moves for the ever-evolving Atlanta Falcons' defense.
The Falcons on Wednesday released safety Dashon Goldson and signed defensive lineman Cliff Matthews. The Falcons needed help on their defensive front after end Derrick Shelby was placed on injured reserve with a torn Achilles tendon, ending his season, on Tuesday.
The moves are the latest attempts for the Falcons, who play San Diego on Sunday, to compensate for injuries.
Atlanta lost veteran linebacker Sean Weatherspoon to an Achilles tendon injury earlier this month. Rookie linebackers De'Vondre Campbell and Deion Jones were still limited by ankle injuries in last week's 26-24 loss at Seattle. Veteran linebacker Paul Worrilow has missed most of the season with a groin injury that required surgery.
Campbell missed four games before making his return in a backup role with three tackles at Seattle. Campbell and Jones, who also played as a backup last week, were expected to be key additions to the defense. A third rookie starter, safety Keanu Neal, missed the first two games following a preseason knee injury.
The Falcons (4-2) have somehow kept the defense together through the constant changes. A big key the last two weeks was safety Kemal Ishmael's move to linebacker. Ishmael had 10 tackles in a win at Denver two weeks ago and had eight stops against Seattle.
''I think it really just shows the resiliency and the next man up mindset,'' Campbell said Wednesday. ''We have four of our primary players just out like that and to have players like Ish step up and learn the linebacker position in a week and play two really good games against Denver and Seattle, it just shows our resiliency as a team.''
Campbell and Jones are hoping to make only their second start together against the Chargers.
The Falcons were counting on Campbell (6-5, 239) to add the size and athleticism needed for pass coverage on tight ends. That will be an especially important assignment against San Diego tight ends Antonio Gates and Hunter Henry.
Campbell acknowledged he wasn't at full speed last week.
''After being out for about a month, I felt I was kind of slow, just trying to get back used to being in the game and at game speed,'' he said.
Matthews, who played for the Falcons from 2011-14, was released by Tampa Bay on Sept. 3. He worked out for the team Wednesday morning and was in his first practice a few hours later. He was still with Atlanta for coach Dan Quinn's minicamp and training camp in 2015, so he said he shouldn't need much time to be ready.
''I'm extremely familiar with the defense,'' Matthews said. ''I'm pretty familiar with everything. So whatever coach needs me to do, I'm going to take advantage of it.''
Shelby, signed from Miami to help boost the pass rush, had eight tackles in six games, including four starts, this season. Quinn said outside linebacker Courtney Upshaw will work at defensive end.
Quinn said the constant adjustments are not difficult ''because we do preach versatility.''
''That's why we play guys at different roles and at different spots,'' Quinn said. ''... Knowing the next guy is up, we really don't talk a whole lot about it. It's knowing if you're here, you're counted on to play well.''
Goldson played as a backup in four games after signing with Atlanta on Aug. 28.
NOTES: Quinn said he talked with the NFL office this week about the play where no penalty was called on Seattle CB Richard Sherman's apparent pass interference with Falcons WR Julio Jones late in last week's game. ''I will keep that conversation private,'' Quinn said. ... The Falcons also signed LB Josh Keyes to their practice squad. ... WR Taylor Gabriel (concussion protocol) and CB C.J. Goodwin (hamstring) did not practice. ... The Falcons will wear their throwback black uniforms.
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