Assessing free agent value through comparable players: cornerback

With only two teams remaining to compete in the Super Bowl, the offseason is in full swing for the rest of the NFL and football pundits. We at PFF are also getting into the action with the launch of our 2020 Draft Guide and new Free Agency Rankings tool, which allows you to sort by position and team needs and includes contract projections from OverTheCap as well as historical grades and wins above replacement numbers for the past three seasons.

I am also doing a series of articles that will go through our top-4 ranked free agents at each position (excluding QBs), using their past stats to match them with historical players. Once we have a sample of similar players, we can see how those similar players performed in subsequent seasons to get an idea of the current player’s range of outcomes.

This system is similar to FiveThirtyEight’s CARMELO player projections, only it is applied to football and uses PFF’s WAR metric as the proxy for player value.

In earlier research, I looked at historical WAR and salary cap figures to derive the approximate cost of a win. Adjustments to our WAR calculation and the ever-rising NFL salary cap has moved the current estimate for the price of a win for spending on unrestricted free agents at 34.2% of the cap, or $68.4 million based on an assumed 2020 cap of $200 million.

Buying wins in free agency is an expensive proposition, but the value of each incremental win for a playoff-caliber team cannot be understated. This year, teams are going to have tough decisions on how to spend that money. The first installment on wide receivers, then running backs and tight ends, offensive linemen, defensive interior, edge defenders, off-ball linebackers, and safeties have already been published. In this article, we’re forecasting free agents at the cornerbacks.

Methodology

For each of the safeties below, the closest comparable players were found by measuring the similarity between them based on several features — age (within one year), WAR, previous-year WAR, PFF coverage grade, slot corner alignment frequency and WAR per snap the past two seasons.

The most similar players across these metrics are grouped together to calculate the expected WAR numbers for 2020 and 2021, with the weight of each comp reflecting the level of similarity. I didn’t use the same number of comps for all players, as it is more difficult to find a wide range of comparable seasons for older and particularly unique players.

The first plot displays past and future performance for the free agent based on the comp, the next shows the relevant WAR numbers for each of the comps and the final table gives the dollar-based value figures for 2018-2021, with assumed per-team salary caps of $200 million in 2020 and $215 million in 2021. I decided to restrict the forecasts to the next two years in order to maximize the number of comparable players we have in the dataset, reduce error for longer forecasts and reflect the fact that all but the top-tier free agent contracts in the NFL are glorified two-year deals that give teams the option to continue.

No. 9: Byron Jones

According to our grade-based WAR calculation, Jones’ production fell in 2019 to a still-healthy 0.4 WAR, which ranked 13th among all cornerbacks. Jones will be a slightly older to start next season (28) than the typical player coming off of his rookie deal with the fifth-year option already exhausted. Jones has zero interceptions over the past two seasons, but he has 15 pass breakups and the fourth-best forced incompletion rate of any corner in the game.

Malcolm Butler is Jones’ closest comp as another outside corner whose WAR fell significantly leading into the same age season. There is a low floor natural at the position where it more difficult to project production and assess play outside of primary coverage.

OverTheCap sees Jones inking a five-year contract worth $16 million per season, including $50.5 million fully guaranteed. The expected comps point to Jones as a value this offseason, but also a risk with a long history of cornerbacks moving teams and failing to perform under new schemes.