Detroit is a solid bet to underperform expectations this year. Let’s learn about “Weak Link” systems.
The Green Bay Packers play in a very difficult division. At least, the NFC North was a very difficult division last year, and it will probably be pretty good in 2025, but there are some question marks that have started to pop up. The Vikings are making a major change at quarterback and, of course, the Bears are counting on Ben Johnson to resurrect quarterback Caleb Williams, because that is what the Bears do.
You don’t hear too much about the Lions, however, and I would like to talk about the Lions because I think there’s a strong case to be made that they fall off of a cliff. At least a bit — keep in mind that they won 15 games last season, and so they’re standing on a pretty high cliff.
When forecasting NFL teams, the most important single concept to understand is likely the “weak link system.” While things like fumble luck and injuries will be major factors for any team, they don’t really reflect any information about the underlying talent or roster construction. We can, to some small extent, project how lucky or unlucky a team will be compared to last year and that’s useful, but it’s not really information about the team.
When I make projections, aside from the above “luck” factors, I also take a long look at defensive performance in general. Offensive performance tends to be more stable from year to year (more on this in a second), but defensive performance fluctuates wildly, for two main reasons:
- The defense does not control the ball, and so the agency of the defense is fundamentally limited. The difference between a good defense and an average defense can be as simple as the number of times each faces some combination of Patrick Mahomes, Josh Allen, Lamar Jackson, and Joe Burrow.
- NFL defenses are a weak link system, meaning their overall production is much more susceptible to changes in personnel than is the case on the offense.
Think of it this way: If your number two receiver gets hurt, you have several options to compensate. You can ask more of your number one and divert targets to him. You can run the ball more or use more 12 personnel to get an extra tight end on the field instead of an extra receiver. It’s not as if the injury won’t do ANY damage at all, but since you control the ball, you get to dictate how you solve this problem.
On the defensive side though, it’s a completely different story. If your number two cornerback is injured, you CANNOT ask more of your number one corner. As most NFL defenses run nickel as a base with two outside corners and a slot specialist on the field, you are either forced to move your slot/nickel corner outside and bring in a bench player to cover the slot or bring in a backup outside corner. Regardless of the choice you make, your fourth best corner is now on the field, and he’s wearing a giant glowing target on his back. In short, you can adjust to losing WR2 by throwing more to WR1, but when you lose CB2, the result is more targets for CB4.
The Lions found this out in their playoff loss to the Commanders last year when Kindle Vildor was forced into major action due to a litany of injuries in the secondary and got toasted for 136 yards and a touchdown. Detroit’s defense faced injury issues for much of the year, starting with an injury to star Aidan Hutchinson, but they still held on to finish 5th in overall defensive DVOA in the regular season. Unfortunately, the dam finally broke in the playoffs, as the Lions were unable to stop the Commanders. Jayden Daniels threw for two scores and the Washington running backs combined for three more as the Commies offense put up 38 points (note that Washington got an extra seven points on a pick-six from Jared Goff).
The Weak Link System on Offense
But defense isn’t the only weak-link system in football, and the surprise retirement of outstanding 29-year-old center Frank Ragnow may presage another cascade collapse in Detroit. Ragnow has spent every season of his seven-year career in Detroit, and after a rookie season in which he was merely average, he’s never posted a PFF score under 75 while eclipsing the elite 80+ tier four times, including in 2024. The Lions have had no worse than the third best line in football since they drafted Penei Sewell in 2021, with Ragnow, Sewell, and Taylor Decker anchoring things.
Detroit’s guards last season were Kevin Zeitler, who is now 35 and has moved on to Tennessee, and Graham Glasgow, who is about to turn 33. Even before the Ragnow news, the Lions were already slated for some major shuffling on the interior line, with 2024 sixth rounder Christian Mahogany and 2025 second rounder Tate Ratledge slated to take over at guard (though Glasgow is still on the team). Ragnow’s current backup is former UDFA Michael Niese, and so what was an absolute rock of a line is now primed to turn over its entire interior. And while Sewell is still there and very much in his prime, Decker is entering his age 32 season and has been bitten by frequent, nagging injuries.
This is also one of the worst possible moments for the Lions to be experiencing massive turnover on the line, as the team has a new offensive coordinator. They will be moving from the outstanding Ben Johnson to John Morton, owner of the worst Wikipedia page for any high-level coordinator in the NFL. Offensive line continuity is one of the best predictors of offensive line play, and the Lions are now a mess on that front.
And importantly, the offensive line is also a weak link system, as defensive coordinators can target the weak link via pass rush. Even if the offense provides that player with help in the form of a double team or tight end chip, that help comes at a cost.
The Lions are especially susceptible to this particular weak link system because of Jared Goff’s reliance on good line play. Goff is a good quarterback, but few quarterbacks have splits between clean pockets and pressure that are as severe as his. Although, to his credit, he has improved against pressure, he is more susceptible to pressure, and specifically up-the-middle pressure, than most quarterbacks. In fact, against the Commanders in the playoffs, line breakdowns cost Goff a fumble and they were a direct cause of one of his three interceptions.
Rushing Efficiency
Detroit also susceptible in the running game, where last season Jahmyr Gibbs and David Montgomery combined for 2187 yards on 435 carries, while scoring 28 touchdowns. Gibbs in particular has become a star along the lines of Saquon Barkley and Derrick Henry and ranked seventh overall in Rushing Yards Over Expected per Attempt last season. As a team, the Lions were fourth in running success rate in 2025, and two of the three teams ahead of them benefitted from outstanding quarterback scrambling (Baltimore, though Derrick Henry is obviously outstanding even without Lamar Jackson, and Washington). Essentially, no other rushing attack in the league, save Atlanta, left their offense in better shape after any given carry.
The Lions run and run a lot. In 2025 they had 478 carries from all running backs combined and were successful on 44.8% of those runs. The Packers gave the ball to their backs 446 times and were successful on 41.9% of runs. That may not seem like a huge difference, but the baseline for the running attack is already inefficient, and if you fall below a 44% success rate, your run game suddenly plunges from a positive EPA endeavor into the negatives. The Lions were one of only six teams to post a positive rushing EPA last year, and in the aggregate, they were responsible for about 10 points of EPA. The Packers, on the other hand, lost about -0.03 points of EPA per rush (11th), and over the course of the season, the run game cost them roughly two touchdowns (-13.38 EPA).
Even though the run game is often a negative efficiency provider, you still need to run the ball for the passing game to function properly, and if you can squeeze actual positive value out of the run game, it’s an enormous boost to your overall offense. That said, it’s easy to see how the changing offensive line in Detroit could have a major impact. Gibbs and Montgomery are excellent players, but so was Saquon Barkley when he was a Giant instead of an Eagle. A downgrade in line play can tank even the best backs, and if the Lions fall from their current success rate position just a few spots, they could easily lose something like 21-24 points of value next season.
It’s possible I’m making a mountain out of a molehill. After all, the Lions have been one of the best organizations in the league over the last several years. This is not a situation where we laugh and point at the Bears and assume the worst, and the Lions may have a very solid succession plan in place.
That said, it’s hard to ignore the sheer magnitude of changes this team has experienced. Ben Johnson and Aaron Glenn have moved on to head coaching jobs; Aidan Hutchinson is returning from a catastrophic injury; the defensive backs are all, to some extent, returning from injury; and one of the true anchors of a great line just decided to hang ‘em up. That’s a lot of shocks to overcome, and when you win 15 games, no matter how good you are, you’re already facing some regression headwinds. There is virtually no chance the Lions repeat their 15-win performance, and I won’t be surprised if they wind up closer to 9 or 10 wins this season.