The Detroit Lions' defense does not have a lot going it lately. The pass rush has been lacking, and the only potential help that's coming is a 36-year old Bruce Irvin. They aren't generating turnovers, and while the run defense is still good it hasn't been as stifling lately,
Schematically, defensive coordinator Aaron Glenn is struggling to marry pass rush and coverage. Those two things have to work in concert. If coverage is too accommodating, the pass rush can't get home. If the pass rushers don't win fairly quickly, the coverage has to hold longer.
We do know the Lions are blitzing less this year (24.5 percent) compared to Glenn's first two years as Lions' defensive coordinator.
From the start on Thanksgiving Day, the Green Bay Packers came out aggressive and Jordan Love picked apart the secondary. As is common, Glenn never really changed anything to adjust to what was going on and stem the tide. Sending extra rushers more often? How about changes in coverage?
Detroit Lions' inability to adjust defensively was again exposed by the Packers
Russell Brown of Lions Wire did a film breakdown of the Lions' defense from recent games, and it's well worth the time to check out. The thesis is essentially that Glenn is trying a lot of different things, with schematic decisions and lack of good fundamentals equally to blame for what's going wrong.
Ted Nguyen of The Athletic (h/t to Colton Pouncy of The Athletic), pointed to how heavily the Lions ran man coverage against the Packers.
"Perhaps the Lions' staff's biggest mistake was playing an inordinate amount of man coverage against the Packers. Maybe defensive coordinator Aaron Glenn assumed they could bully the Packers' young receivers. Coming into the game, the Lions played man coverage on 24.3 percent of dropbacks. They more than doubled that rate against the Packers, playing man on 51.9 percent or dropbacks. I think the idea was to force Love, who had been one of the most inaccurate quarterbacks in the league, to throw into tight windows. Only, they couldn't cover the Packers' receivers and Love was on fire (Thursday). The theory has merit, but the problem was that they never adjusted."
In his piece, Brown noted how the Packers' offense uses motion at a top-10 rate in the league (61 percent, per Sports Info Solutions). Using motion, on a very base level, reveals whether coverage is man or zone. The Packers revealed the Lions being in man coverage, and attacked it accordingly.
As Pouncy noted, the four games where the Lions have played man at the highest rates have yielded the best or second-best single game EPA per dropback for those quarterbacks.
In certain games, see the Seahawks, Ravens and Chargers games this year before Thanksgiving Day, Glenn is unable to adjust to what an opposing offense is doing. It's impossible to just scrap the game plan and start over in-game, but an adjustment here and there would be nice to see when things are going poorly.
The Packers outcoached the Lions in all facets last Thursday, as admitted by Dan Campbell. But it may not have been more evident than when Green Bay had the ball against the Detroit defense.