Biggest injury loss for the 49ers defense may be a player you seldom hear of ...

[Auggie]

defensive end Clelin Ferrell, member of the starting unit and run game specialist. He was lost for the season in Week 18 to a knee injury. His absence has been filled by mid-season additions Chase Young and Randy Gregory, fine players, but specialists against the pass, not run. It helps explain the resurgence of opponent running attacks as seen in the playoff games versus Green Bay and Detroit. As Eric Branch of the San Francisco Chronicle explains:

After allowing 89.7 rushing yards a game in the regular season, which ranked third in the NFL, the 49ers are allowing 159 in their two playoff games.

The biggest difference? It isn’t hard to identify. Defensive end Clelin Ferrell, who played in their base defense, typically employed in non-passing situations, made all 17 regular-season starts. However, Ferrell suffered a season-ending knee injury in Week 18 and his role has been shared in the playoffs by Young and Randy Gregory, who were both acquired in mid-season trades.

Both Young and Gregory are known more for their pass-rushing ability. And the Lions had success running to their side. On their final drive of the first half, for example, running back David Montgomery had a 9-yard run when right tackle Penei Sewell sealed off Gregory. Four plays later, on 3rd-and-12, Gibbs ran for 13 yards around left end because Young crashed inside at the snap.

Earlier this month, before their first playoff game, pass rusher Nick Bosa noted both defensive ends are still finding their way in the 49ers’ scheme when asked about Ferrell’s absence.

LINK (paywall): https://www.sfchronicle.com/sports/49ers/article/49ers-game-review-lost-amid-euphoria-problems-18636294.php

Bosa (from the link): "Randy Gregory and Chase are still learning, so they’re going to have to learn quick on the run and be ready to fill those shoes. Clelin brought probably the best effort of anybody on the team."

Andy Reid is aware of this, of course.