Since the season ended, much of the discussion surrounding the Lions has focused on the offense.

Dan Campbell fired offensive coordinator John Morton and brought in two new assistants — offensive coordinator Drew Petzing and former Giants OC Mike Kafka. They feel like reasonable hires for an offense that didn’t meet expectations in 2025, despite ranking in the top five in scoring and yards per game.

If that’s the bar for the offense, though, what should we make of the Lions’ defense? It’s a fair question.

Let’s review the year that was for Kelvin Sheppard’s defense, and where the Lions could go from here.

Traditional and advanced statistics

Before we dive into specifics, let’s take a look at where the Lions ranked in various statistical categories (via TruMedia).

• Points per game: 24.3 (22nd)

• Yards per game allowed: 331.9 (18th)

• Rushing defense: 114.5 (14th)

• Pass defense: 217.4 (20th)

• Explosive play rate: 11 percent (18th)

• Explosive run rate: 6.1 percent (ninth)

• Explosive pass rate: 15.9 percent (27th)

• Takeaways: 19 (19th)

• Sack rate: 8.1 percent (seventh)

• Pressure rate: 36.8 percent (17th)

• Defensive success rate: 60.4 percent (seventh)

• Defensive rushing success rate: 61.4 percent (10th)

• Average time to throw: 3.00 seconds (30th)

• Average time to pressure: 2.86 seconds (30th)

• Third down conversion rate allowed: 36.9 percent (ninth)

• Three-and-out rate: 35.3 percent (seventh)

• Fourth down conversion rate allowed: 65.6 percent (25th)

• Red zone efficiency: 59.6 percent (21st)

• Goal-to-go efficiency: 80 percent (26th)

A look at the scheme

When Aaron Glenn departed for the Jets last year, Campbell set out to keep Detroit’s heavy-man system in place. The Lions had the personnel to run it and hoped better health would yield better results. It’s easy to forget considering how quickly the injuries piled up, but the 2024 Lions finished as a top-10 scoring defense. Campbell filled the position internally, promoting Sheppard from linebackers coach to DC.

While Glenn and Campbell spent years quietly preparing Sheppard for this role in hopes of continuity, he was always going to put his own touch on the defense. We saw that in 2025.

Base defense: No team played more 4-3 (four defensive linemen, three linebackers) than the Lions this past season. Per TruMedia, the Lions’ 4-3 rate of 60 percent ranked first in the NFL, accounting for 630 of their 1,050 defensive snaps. League average was 12.8 percent. That shouldn’t come as a surprise — the Lions also led the league in 2024 — but there was a noticeable uptick in usage under Sheppard. In Glenn’s final season, the Lions played 4-3 on 38.7 percent of snaps. League average was 13.5 percent that season.

A couple of points worth noting: The Lions held their own in their base package, with a defensive success rate of 61.1 percent (fifth) when playing three linebackers. Injuries at outside corner forced nickel Amik Robertson to play more snaps on the outside than expected, and there wasn’t a trusted reserve. The Lions leaned into 4-3 as a result. However, when you look around the league, some of the best defenses are deploying elite nickel corners or playing it at a high rate.

The Seahawks (first), Texans (second), Patriots (fourth) and Eagles (fifth) account for four of the top five scoring defenses. They also account for four of the six highest nickel rates — a topic colleague Ted Nguyen touched on this month. The Lions, meanwhile, ranked dead last.

With Alex Anzalone set to hit free agency, it’ll be interesting to see where the Lions go from here. If they want to continue playing three linebackers, they’ll need to either pay Anzalone or find his replacement. If not, they could move Derrick Barnes to Anzalone’s position (will) and look to play more nickel.

Coverage schemes: Under Glenn, in 2024, the Lions led the league in man coverage rate at 41.2 percent. Under Sheppard this past season, the Lions fell all the way to … third, at 31.8 percent. A bit of a change in rate, but still among the league leaders.

In terms of how the Lions fared in man coverage, it was a tale of two halves. From Weeks 1-9, the Lions ranked third in defensive success rate, fifth in completion rate allowed, sixth in defensive pass EPA/dropback and 10th in yards per play in man coverage. From Weeks 10-18, they ranked 28th in defensive success rate, 24th in completion rate allowed, 28th in defensive pass EPA/dropback and 31st in yards per play in man coverage. Injuries were a factor, of course, but things fell apart in the second half. More on that later.

Blitz rate and pressure: A staple of Glenn’s defense was a high blitz rate. From 2021-24, the Lions ranked sixth in blitz rate among teams at 30.1 percent and 10th in pressure rate during that span at 35.3 percent. But in 2025, Detroit’s blitz rate fell to 23.7 percent — 20th in the league — and its pressure rate ranked 17th at 36.8 percent. The biggest difference, though, was the blitz’s effectiveness.

In Glenn’s final year, the Lions’ defensive success rate when blitzing ranked ninth. In 2025, they ranked second, trailing only the Seahawks. So while Sheppard didn’t rely on the blitz to generate pressure as often as Glenn did (who was without Aidan Hutchinson for much of the 2024 season), when he did dial it up, they were one of the NFL’s most efficient teams.

Personnel and injuries

We’ve talked about the scheme and how it performed in 2025, but what about the personnel? Most coordinators will tell you their scheme is only as good as the players on the field. What about the players off of it?

Let’s get the injury discussion out of the way. The Lions were without CB1 (D.J. Reed) for six games, CB2 (Terrion Arnold) for nine games, All-Pro safety Kerby Joseph for 11 games and Pro Bowl safety Brian Branch for five. Admittedly, it’s a lot to navigate. The Lions were able to, at times — the “Legion of Whom” win over the Bucs stands out — but other times, it felt like Sheppard and the coaching staff didn’t have answers.

When Branch was injured in Week 14, the Lions were down to one healthy starter in Reed, who was still shaking off the rust from a hamstring injury that sidelined him for six weeks. To account for the secondary losses, Sheppard deployed more zone coverage — albeit with mixed results. From Weeks 15-18, the Lions were much more balanced, playing man at the 14th-highest rate and zone at the 13th-highest. While their defensive EPA per dropback ranked 12th in that span, their run defense was left vulnerable. Detroit’s defensive rushing success rate from Weeks 15-18 ranked 31st, and the team allowed a league-high 6.0 yards per rush in that span.

Glenn’s defense in 2024 dealt with major injuries to its front seven, losing Alim McNeill, Hutchinson, Barnes, Anzalone and Davenport to injured reserve at various points. The secondary, save for Carlton Davis III, was relatively healthy. Sheppard’s secondary, meanwhile, saw its entire starting unit land on IR. Reed suffered a hamstring strain and didn’t look the same upon his return. Arnold underwent season-ending shoulder surgery. Branch tore his Achilles in December and could miss significant time in 2026. Joseph is nursing a knee injury that didn’t improve despite plenty of rest. The hope is that the offseason will provide ample recovery time, but it’s something to monitor.

If the Lions are going to continue running this scheme — one that relies heavily on the health of its secondary — they could really use a quality running mate for Hutchinson. They need a pass rusher who can win on his own — and quickly. Detroit’s average time to pressure of 2.86 was the third-slowest in the NFL last season, per Next Gen Stats. If that’s not in the budget, and the Lions don’t want to reach for an edge they don’t love in the draft, they will either need to hope for better health or make changes to the scheme or personnel. Maybe both.

What changes could be made?

You’d expect some growth from Sheppard as he enters Year 2 in Detroit. From Weeks 1-9, the Lions ranked third in defensive success rate at 62 percent, trailing only the Broncos and Browns and ahead of the Rams (fourth), Texans (fifth) and Seahawks (sixth). They were top 10 in points per drive, yards per game, EPA per snap, defensive rushing success rate and defensive pass EPA per dropback, as well as 13th in overall scoring. They put some solid film on tape under Sheppard.

Is Sheppard the type of coordinator who can keep defenses afloat when injuries pile up, like Robert Saleh did this past season? From Weeks 12-18, the Lions ranked 30th in yards allowed (389.1), 28th in yards per rush (4.9), 29th in passing yards per game (253.4) and 27th in points per game allowed (28.1), while allowing the second-highest fourth-down conversion rate (80 percent) in that span. Sheppard tried to make adjustments rather than sticking to his scheme with players who weren’t equipped to run it, but it didn’t yield the desired results.

It might be wise for the Lions to look into bringing in an external senior defensive assistant for Sheppard. Glenn had Dom Capers and John Fox as sounding boards in that role. Maybe a veteran coach like Chuck Pagano — who coached Sheppard in Indianapolis and has experience overseeing NFL secondaries — could be that voice. He came out of retirement last year, serving as senior defensive assistant/secondaries coach for the Baltimore Ravens. Perhaps he’s available now that John Harbaugh is out.

As for the roster, it’s too early to tell what changes could be coming. The Lions have a chance to reshape the defense. Here are notable Lions free-agent defenders set to hit free agency:

• LB Alex Anzalone

• LB Malcolm Rodriguez

• CB Amik Robertson

• CB Rock Ya-Sin

• Edge Al-Quadin Muhammad

• Edge Marcus Davenport

• Edge Josh Paschal

• DT Levi Onwuzurike

• DT Roy Lopez

• DT DJ Reader

The four names that catch your eye on that list are Anzalone, Robertson, Muhammad and Reader. All four expressed interest in returning, but acknowledged that their time in Detroit may be over. Anzalone, Reader and Muhammad are all 30 or older and could look to cash in. Considering the Lions drafted DT Tyleik Williams 28th a year ago, this could be it for Reader. Is it worth signing Muhammad, 31 in March, to an extension? He recorded 11 sacks, but 7.5 of them came in three games, and it often felt like he wasn’t trusted to defend the run. Maybe this is the year they look to draft a young, cost-controlled edge rusher on Day 1 or Day 2. They haven’t since 2022.

If Anzalone walks, the Lions could move Barnes to will linebacker. In that scenario, it would make sense try to backfill the sam position with a linebacker who has more pass-rush juice than Barnes — should they continue to deploy a high 4-3 rate. Given the value of nickels in the league, could the Lions look to upgrade there and move on from Robertson? He’s a fan favorite and a good locker room presence, but allowed a passer rating of 110.5 when targeted (105 out of 124 qualified CBs, per PFF).

Some subtle tweaks and upgrades, whether it be free agency or the draft, could go a long way toward solidifying a defense that still has a strong nucleus in place. For all the attention the offense has received since the season ended, the defense must improve to balance things.