Dynasty, in Theory: Defense Doesn't Matter (in April)

There's a lot of strong dynasty analysis out there, especially when compared to five or ten years ago. But most of it is so dang practical—Player X is undervalued, Player Y's workload is troubling, the market at this position is irrational, and take this specific action to win your league. Dynasty, in Theory is meant as a corrective, offering insights and takeaways into the strategic and structural nature of the game that might not lead to an immediate benefit but which should help us become better players over time.

Turning the Lights Out on the Season

For most leagues, Week 14 closed the book on the regular season. While many teams have been mathematically eliminated for a while, Tuesday morning marked the official end of the season for around half of all dynasty teams. No more lineups to be set, no more games to be played, all that remains is to clean out your locker and turn the lights off on your way out the door.

I would love to believe that none of my readers would count themselves among that number, but base rates rule everything around me (B.R.R.E.A.M.), so I'm guessing the true value is... fairly close to 50%. That's unfortunate, but it's also an opportunity. Once freed of the responsibility of fielding a valid lineup, we can cut all our dead weight and fill those spots with lottery tickets that have a chance of paying out next year.

And for most teams in most leagues, the place to start is simple: cut all of your defenses.

Defense Doesn't Matter (in April)

Some might find this counterintuitive. If your league breaks down scoring by position, I suspect you'll see the difference between the team with the most productive defenses and the team with the least is quite substantial. Having the highest-scoring defenses provides a significant edge in fantasy.

In the most extreme example, one of my leagues uses heavy performance-based scoring, with defenses losing a point for every point they allow. In that league, the difference between the Houston Texans (235 points) and the 12th-place Cleveland Browns (131 points) is bigger than the difference between Amon-Ra St. Brown (267 points) and 37th-place Keenan Allen (165).

Cutting the Texans might seem crazy; if the best defenses are so valuable, shouldn't you keep Houston so you can benefit next year, too? If holding defenses in April gave you a better shot at rostering one of the highest-scoring defenses in October, it'd easily be worth doing.

But it doesn't, so it's not. (At this time last year, I was writing this about the first-ranked Minnesota Vikings. So far this year, they rank 13th.)

Defensive Performance is Only Weakly Predictive

An anecdote is a datum, but it is not data, so let's look at a larger sample. I've charted all defenses from 2019 to 2024 in Footballguys' standard scoring system, which is a bit less extreme than that from my home league.

If you look at the Top 10 defenses from any given year, the average rank will be 5.5. If defense was perfectly stable from year to year, those same ten defenses would have an average rank of 5.5 again the next year. If performance was perfectly random, they'd have an average rank of 16.5.

The Top 10 defenses in 2023 had an average rank of 16.5 in their follow-up campaign. The Top 10 defenses from 2022 had an average rank of 14.6 in their follow-up campaign. 2021's top defenses ranked 13.3 the next year. 2020's had an average rank of 12.1, and 2019's ranked 12.8. All told, Top 10 defenses from 2019-2023 had an average rank of 13.8 in their next season.

A Top 10 defense in Year N had a 44% chance of repeating as a Top 10 defense in Year N+1. That sounds good, but remember that if you picked a defense entirely at random, there'd be a 31% chance of it finishing in the Top 10 the next year, too.

Where Do Top Defenses Come From?