At this juncture in the season, the Detroit Lions defense finds itself grappling with a barrage of injuries that have significantly impacted their performance on the field. The list is long, starting with John Cominsky’s season-ending injury in the summer, followed by Aidan Hutchinson and more recently, Alex Anzalone, who suffered a broken forearm in week 11 against the Jacksonville Jaguars. Since then, the Lions have faltered, allowing 30+ points in three of their last four games and slipping to the 31st-ranked pass defense in the NFL.

On Monday night against the San Francisco 49ers, Detroit’s defensive struggles were glaring. Brock Purdy, the 49ers’ quarterback, had a field day, completing 27 of 35 passes for a whopping 377 yards and three touchdowns. While Kerby Joseph did manage to snatch two interceptions, it wasn’t enough to counteract Purdy’s aerial assault on the Lions’ defense.

A closer look at the game’s finer details reveals that Detroit’s linebackers had a tough night against the pass. Ben Niemann, Jack Campbell, and Jalen Reeves-Maybin surrendered a perfect 10 receptions on 10 targets for 162 yards and a touchdown. Yet, amidst these deficiencies, the Lions managed to muster crucial plays when it mattered most.

Let’s dissect some key moments from Monday night’s game. Wheel routes have emerged as a kryptonite for Detroit’s defense, and the 49ers exploited this deficiency as if they had found the Lions’ secret vulnerability. One pivotal play featured Jalen Reeves-Maybin getting outmaneuvered on a wheel route by 49ers running back Isaac Guerendo.

The Lions, in their nickel package, faced a trips right formation from the 49ers. The scheme seemed to call for man coverage.

However, Reeves-Maybin found himself flat-footed, turning back toward the quarterback and losing vital ground. Guerendo seized the moment, creating ample separation and converting the opportunity into a completed pass.

The defensive miscues didn’t stop there. Another illustrative play showcased the Lions in a single high safety look, signaling a Cover-1 man defensive scheme.

Before the snap, the 49ers put a tight end in motion. Once the ball was in play, Jack Campbell, Ben Niemann, and Brian Branch collectively overcommitted to the right, leaving the middle of the field unguarded.

This lapse gave Purdy an unobstructed passing lane for a critical first down, disrupting the Lions’ defensive rhythm.

Adding context to these shortcomings, Detroit’s defense has visibly deteriorated since Anzalone’s injury, as demonstrated by a declining defensive DVOA over the last five games. This downturn includes record lows over the past three matchups.

Nevertheless, the Lions’ resilience shone through with timely turnovers. Kerby Joseph’s interception was a critical play. Despite the receiver having 6 or 7 yards of separation, Joseph’s keen reading of the play allowed him to intercept the pass, marking a transition that set the Lions up to run down the clock and cushion their lead.

In sum, while the Lions’ defense is managing to keep the ship afloat, forcing those two interceptions on Monday night was pivotal. As they begin to reintegrate injured players across all phases, it’s crucial that Detroit works on mitigating recurrent errors on passing downs. Their defensive predictability, particularly with single high safety alignments hinting at Cover 3 or Cover 1 man defenses, has been exposed.

Going forward, strategic changes are necessary. More two-high safety looks could offer better disguise for their Cover 1 or Cover 3 schemes, easing the transition into a Cover 2 defense and thereby enhancing versatility on the defensive front. The Lions are in for an intriguing stretch as they hone these tactics in their bid to stabilize the defense during this critical phase of the season.