In correlation with the Detroit Lions winning eight of their last 10 games last season, the defense performed noticeably better. The firing of defensive backs coach Aubrey Pleasant was an easily marked turning point, but defensive coordinator Aaron Glenn made some adjustments too.
Overall though, the Lions still finished among the worst defenses in the league last year (last in total defense; 28th in points allowed). The defensive overhaul this offseason was focused on the secondary (Cameron Sutton, C.J. Gardner-Johnson, etc.), and a first-round pick was used on linebacker Jack Campbell.
It will be up to Glenn to figure out how to deploy his new pieces, and the Lions' defense is almost automatically going to be better this year. But early tests will come against the Kansas City Chiefs in Week 1, and in Week 2 against a Seattle Seahawks' offense the Lions did not force to punt in last year's matchup.
Detroit Lions' "Achilles" heel lands as obvious possible concern
In his piece projecting the hierarchy in the NFC North this season, where he named the Green Bay Packers as the No. 1 team, NFL.com's Bucky Brooks pointed to what he sees as the Lions' potential Achilles' heel.
"Defensive coordinator Aaron Glenn must find a way to keep his unit from faltering as the team's weak link. Last season, Detroit's defense was absolutely horrendous during the 1-6 start. To his credit, though, Glenn turned things around in the Lions' 8-2 finish by tweaking his personnel and implementing a schematic shift that enabled a group of young defenders to play fast and furious..... This influx of talent should significantly raise the floor on the Lions' defense, though Glenn has to make sure everything comes together and the chemistry is right. It looks much better on paper, but the game is played on the field.
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In a broad sense, and very early with only the general positivity of OTAs in the books, the Lions' new defensive pieces gelling and ultimately playing well may not be a huge concern. But it is absolutely a potential thing, as new players learn to work together, trust each other, etc.
If the Lions are going to take the next step this season, the defense can't be among the worst in the league in any area. The talent is upgraded, it's now a matter of it showing on the field as Glenn drives the ship.