“The grade is the grade.”
That's the line I got from an NFL player after he asked for an explanation about his particular season PFF grade. After I went through the different ways to interpret or use the grade, the player concluded, “The grade is the grade.” It was his way of accepting that PFF quantifies how well a player performed his role, and they (as players) live with it.
There are many ways to use PFF grades, and they go beyond the constructs of just one number. This week, the Philadelphia Eagles traded two draft picks to the Detroit Lions in exchange for cornerback Darius Slay in an aggressive move to re-tool their secondary. Slay is coming off the second-lowest PFF grade of his career and the worst since his rookie season of 2013. However, the PFF consensus is that it’s the right move for the Eagles and one that should pay off. Why the discrepancy? It’s all about how to use the PFF grade and data in order to make an informed decision.
Let’s have a look.
Look at more than one year of data
When evaluating a player, it’s easy to look at his most recent season and only focus on that year when projecting him forward, but the entire body of work must be considered. While we pride ourselves on grading every player on every play from a production standpoint, we realize that there is far more than just an overall grade that defines a player’s performance and value. As we’ve studied the PFF data through the years, we’ve learned numerous lessons regarding best practices in player evaluation:
• Use more than a one-year sample of data.
• Find the components of each position that are most stable and unstable from year to year.
• Use the entire database of information to paint the contextual picture regarding a player’s role, usage pattern, supporting cast and strength of opponents.
We encourage our PFF ELITE users to get the most out of Premium Stats version 2.0, as it has grades and stats for every snap of every player. Using all the tools at your disposal is more important than just using one solitary number to tell the story.
However, the grade is the grade.
When a player like Slay, with a history of strong performances, has a down year, it’s fair to take the entire body of work and look into why his grade was lower in 2019. As PFF fantasy football analyst Jeff Ratcliffe points out, Slay’s stretch of opposing receivers was strong in 2019.
Darius Slay shadows in 2019 pic.twitter.com/hJpzo0NWvo
— Jeff Ratcliffe (@JeffRatcliffe) March 19, 2020
Not only was Slay going up against Davante Adams, Stefon Diggs, Allen Robinson and Amari Cooper, but he was doing it in man coverage. The Lions play as much pure man coverage as any team in the league, and over the last two seasons Slay has faced the third-most targets in single coverage during the regular season.
|Single Coverage Targets
Covering receivers in man coverage is one of the most difficult things to do on the football field, as evidenced by the PFF grades when cornerbacks are targeted in single coverage. Only a handful of cornerbacks graded above 60.0 over the last two seasons, as they’re generally going to be targeted when receivers have separation. Slay faced more of these targets than all but two corners.
The new defense in Detroit put a lot of pressure on Slay in man-to-man situations against top receivers, but that’s not the only reason to be more optimistic about his future in Philadelphia.
For cornerbacks especially, you must look at more than one year of data
With cornerbacks, it’s not just a suggestion to look at multiple years of data, it’s a must. Coverage is one of the most unstable measures of play on a football field, as it is largely dependent on the opposing quarterback and receiver. A one-year sample is never enough, and understanding the big-picture development of a player’s career is paramount.
After a slow start to his career with a 50.8 overall grade on 349 snaps in 2013, Slay went on to grade “in the green” in every season from 2014 to 2018, including his peak season with an 80.6 overall grade in 2017 that featured a passer rating of just 55.6 into his coverage.
He’s also been one of the best in the league at breaking up passes, forcing more incompletions than any cornerback in the league since 2014.
Darius Slay: 85 forced incompletions since 2014
Most in the NFL pic.twitter.com/CJIFOhpWgR
— PFF (@PFF) March 19, 2020
Slay’s entire body of work puts him at No. 4 in PFF’s WAR (wins above replacement) metric since 2014, making him an excellent option for the Eagles in exchange for two mid-round draft picks.
Cornerback evaluation must focus on multi-year trends, and while Slay did get beat at a higher rate in 2019, his career data is more informative than just the one-year sample size.
Projecting Slay in Philadelphia
When Slay was drafted in 2013, Eagles defensive coordinator Jim Schwartz was the head coach in Detroit. While they only lasted one year together, that familiarity is another key component in Slay’s projection. Prior to Lions head coach Matt Patricia’s arrival in 2018, Slay had played in defensive schemes that relied on mixing up coverages and playing more zone concepts, and that’s what he will be doing under Schwartz with the Eagles. Over the last three years, the Eagles rank in the middle of the pack in both man and zone concepts, and that coverage mix fits Slay’s skillset better than just playing man coverage on most of his snaps.
— PFF (@PFF) March 19, 2020
The Eagles have thrown a lot of bodies at the cornerback position over the last two years, both by design and by necessity due to injuries, and Slay immediately steps in as their No. 1 option on the depth chart. They’re hoping that his play is closer to the 2014-18 Slay than the one we saw last year.
Given the fickle nature of coverage performance, it’s a safe bet that Slay will bounce back and once again and rank among the league’s best in his new home.