Defensive Positions to Target in Free Agency and Trades

Looking through more than a decade of NFL Plus/Minus data to see which positions retain the most value as offseason free agent and trade acquisitions

Yesterday I published an analysis on the offensive positions to target in free agency and trades, and now we turn to defensive positions. Many of the same macro lessons you can take from that analysis apply here, but there are even more stark and counterintuitive conclusions found digging into the specific defensive positions.

In case you didn’t see yesterday’s analysis, I’ll repost the intro and setup, then dig into the takeaways for defensive positions after posting the visualizations.

I’ve put out a number of posts over the last couple weeks on my player valuation metric, NFL Plus/Minus. There are some cool exercises you can apply the valuation metric on, like my articles on the most valuable offensive and defensive players last seasons, plus my evidence-backed take that Travis Kelce isn’t particularly close to matching Rob Gronkowski’s on-field value.

These analyses looking back can enhance your understanding of where value comes from in the NFL, but more interesting to using the data and value metric to predict where it will come from in the future. We’re about to enter the free agency period of the offseason, which also will included trade acquisitions, sometimes of elite-level players. Having NFL Plus/Minus player valuation data going back to 2006 allows us to see how players acquired via different methods have performed in the past, and then apply those lessons to this year’s free agency class and trade targets.

Isolating player talent and value is extremely difficult, and even more important when a player is taken out of one context (coaching system, surrounding talent) and placed into another. Big free agent acquisitions and trades are risky due to the known effect of new coaching and player interactions, adding a layer of uncertainty to already unstable year-over-year player performance.

There are three places main avenue to acquire talent in the NFL: the draft, free agency (including signing player who were cut by their previous teams) and trading. Trades are the least common, but also can have some of the biggest playoffs. The draft has every position and level of player available, as long as you can identify them with limited opportunities. Free agency should be viewed fundamentally as a way to fill in talent around the roster. The free agent player pool is of a lesser talent (players whose previous team chose to let go or not extend), and opening up contract negotiations to an additional 31 teams naturally raises the contract costs.

WHAT LEVEL OF TALENT IS AVAILABLE IN FREE AGENCY?

Because the beginning of free agency precedes the draft by a number of months, having a general idea of the type of talent and positions that best retain value in free agency (and trades) is key to knowing which players you should then target in the draft. Here I will look specifically at what level of talent for offensive positions is available to acquire in free agency, and how much of a discount can be assumed for future production versus drafted and extended players.

The plot below shows the general range of player-talent historically acquired in free agency by position. The proxy for “talent” here is positional percentile for previous-year NFL Plus Minus on a per-game basis. In order words, the height of the line on the right side of each position represents the higher percentile players at the position, and the left are the lower value players.

I’ve also posted all of the NFL Plus/Minus historical values on the paid subscriber Google sheet. I’d love to see what the analysts among my subscribers can so with the data.