Jets 2021 free agency: Ranking the cornerbacks from best to worst

Ranking 53 impending NFL free agent cornerbacks from best to worst, based on an accumulation of their 2020 statistics. Using an agglomeration of four different key statistics, I ranked the 53 impending NFL free agent cornerbacks that played at least 250 defensive snaps in 2020. This is the third in a series of articles that will rank all of the qualified free agents at key positions of need for the New York Jets - I have already ranked 47 free agent wide receivers and 47 free agent edge rushers. The players were ranked according to their average percentile ranking among 129 qualified cornerbacks in these four statistics: Pro Football Focus coverage grade: PFF's all-encompassing evaluation of a player's performance in coverage based on the grading of every coverage snap. This stat's best attribute is its ability to account for mishaps by the opponent. If a player is burnt in coverage but gets bailed out by a drop or bad throw, his coverage stats will reflect him positively, but PFF's grading system will give him the negative credit he deserves. Passer rating allowed: Passer rating allowed by the player across all targets in his direction. Yards per cover snap allowed: Formula: yards allowed divided by snaps played in coverage. Yards per cover snap is a solid stat for evaluating coverage impact because it accounts for not only a player's ability to limit production on targets in his direction but also his ability to limit targets altogether. It's nice to know what players allow when they are targeted, but it is also important to take into account how good of a job they do at preventing the ball from coming their way in the first place. In a vacuum, players deserve credit for logging a coverage snap without being targeted. Yards per cover snap accomplishes that, while coverage stats that look only at what players allow on a per-target basis do not. Players who are targeted at a low frequency tend to perform well in this stat. Pro Football Focus run defense grade: PFF's all-encompassing evaluation of a player's performance as a run defender based on the grading of every snap against the run. Overall score: The player's percentile rankings in each of the four metrics above are averaged together to create an overall score by which the group was ranked. Of course, coverage is far more important than run defense for a cornerback, so that is why I decided to only include one run defense stat against three coverage stats, making a player's coverage stats responsible for 75% of their overall final score. The chart showcases some other crucial information, including the player's free agency type, exact age to the decimal point on Sept. 1, and their average number of defensive snaps per game. In addition, there are two metrics listed to showcase each player's usage. "Outside percentage" refers to the percentage of a player's snaps in which they lined up as an outside cornerback. Players with a high number in this column typically line up as the outermost cornerback on their side of the field, while players with lower numbers line up more frequently in the slot. "Left side percentage" refers to the percentage of a player's snaps in which they lined up on the defense's left side, showcasing which side of the field their team preferred to use them on. A lower number in this column means that the player was used more frequently on the right side of the field. Here it is: 53 of the top 2021 free agent cornerbacks, ranked from best to worst: Takeaways Robert Saleh's 49ers secondary is sitting pretty Of the top 10 players on the list, four are 49ers that played under Robert Saleh last year. Jason Verrett tops the list after a resurgent season in Santa Clara. A former budding superstar with the Chargers after being taken in the first round of the 2014 draft, injuries destroyed Verrett's career as he played in only six games over a four-season span from 2016-19. In 2020, his age-29 season, Verrett managed to take the field for 13 games, picking up where he left off back in 2015 when he made his first Pro Bowl and was ranked as PFF's No. 2 cornerback. Verrett posted an overall PFF grade of 77.6 that ranked eighth-best among cornerbacks. He was one of only five cornerbacks to allow a passer rating below 80.0 and a yards per cover snap average below 0.90 across over 400 cover snaps, joining Jaire Alexander, James Bradberry, Kendall Fuller, and Jalen Ramsey. Ahkello Witherspoon was stout when healthy, allowing the same yards per cover snap average as Verrett (0.82), which tied them for 11th-best among the 114 corners with at least 200 cover snaps. That was a huge step up for Witherspoon compared to his 2019 season, when he allowed 1.20 yards per cover snap, ranking 64th out of 114. Among corners with at least 300 snaps, Witherspoon had the fifth-best overall PFF grade in 2020 at 80.2. Richard Sherman can still lock up. He allowed the second-fewest yards per cover snap among qualifiers in 2020 (0.43) and the fewest in 2019 (0.44). Seventh-year veteran Dontae Johnson coughed up just 0.87 yards per cover snap over a small sample of 164 cover snaps in 2020, ranking 21st out of 131 qualifiers. San Francisco's primary slot corner over the past two seasons was K'Waun Williams, who proved to be one of the NFL's best coverage men on the inside. In 2020, Williams allowed 0.80 yards per cover snap when lined up in the slot, best among the 33 cornerbacks with at least 150 slot coverage snaps. He ranked 12th out of 39 with a mark of 0.99 in 2019. Altogether, over the past two seasons, Williams logged 489 cover snaps in the slot and allowed 55 catches for 452 yards, no touchdowns, and two interceptions over 80 targets, resulting in fantastic rates of 5.7 yards per target and a 72.5 passer rating. With the Jets in dire need of cornerback help, it would not be shocking at all if at least one of the aforementioned 49ers followed Saleh across the country. For the second consecutive season, Brian Poole is a premier name on the market In 2020, Poole entered March as arguably the most productive cornerback on the free agent market. Fast forward one year, and he is once again one of the best corners set to become available. Poole was graded as PFF's 10th-best cornerback (minimum 300 snaps) in 2020 with a 77.4 overall grade, a tiny tumble from his No. 7 ranking in 2019 with a 79.0 overall grade. He remained stingy in 2020 with no touchdowns, two interceptions, and 267 yards allowed over 40 targets (6.7 yards per target) and 279 snaps (0.96 yards per snap) in coverage. To see Poole get a measly one-year, $5 million deal in 2020 after his outstanding 2019 season was a shock. Is he due for a similar fate in 2019, or will teams be more willing to break the bank for him after he went out and proved that 2019 was no fluke? If the Jets allow Poole to walk, you can't help but turn your eyes back out west to San Francisco and look to K'Waun Williams as a potential replacement in the slot. Looking for a good corner in his prime? Tough luck. Teams will have plenty of options if they are willing to bank on an older player, but the market is light on legitimately good corners who are in or entering their prime. The upper tier of our free agent list is peppered with veterans. Of the top 12 players, 10 will be at least 28 years old when the season begins. There are only five outside cornerbacks on our list who posted an overall score over 60.0 and will be 27-or-younger at the end of the 2021 calendar year: Ronald Darby, Ahkello Witherspoon, Levi Wallace, J.C. Jackson, and Charvarius Ward. Problem is, the latter three are restricted free agents. In Witherspoon's case, teams have to wrestle with the sample size issue. Witherspoon had a career year in 2020, but he only played 334 snaps total. Over a much larger sample from 2018-19 (1,275 regular season and playoff snaps), Witherspoon was a liability, allowing 12 touchdowns and one interception. Darby arguably offers the best combination of age and production among outside cornerbacks who are unrestricted free agents. He was awful for the Eagles in 2019, but after a strong rebound for Washington in 2020, that mess of a 2019 season stands out as a massive outlier in his six-year career. Darby has posted an overall PFF grade above 68.0 in each of his other five seasons, allowing a solid career passer rating of 87.0 outside of 2019. Michael Davis of the Chargers and Shaquill Griffin of the Seahawks are promising wild card options among the younger outside cornerbacks who are unrestricted. Davis allowed a passer rating of just 77.7 in 2020 and has not allowed a 90.0+ rating in any of his four NFL seasons. Over 1,479 career cover snaps, Davis has given up only four touchdowns against five interceptions. Griffin had a down season in 2020, playing at a relatively average level, but he ranked 10th-best among cornerbacks with a 77.0 overall grade at PFF in 2019. Ricky Manning, a newly-hired defensive assistant for the Jets, was with the Seahawks as an assistant defensive backs coach in 2017 when Griffin was drafted and had an impressive rookie season. Looking to the inside, only two slot corners on the list posted a score over 60.0 and will be no older than 27 at the end of the season: Corn Elder and Desmond King. Elder is a restricted free agent. Who said cornerbacks don't age well? As we just went over, the upper echelon of this list is dominated by vets. Teams looking for cornerback solutions on the free agent market will need to be open to running some old pairs of legs out there. We've already discussed 30-plus studs Sherman and Verrett. Xavier Rhodes, who will turn 31 in June, is another familiar name who still has gas in the tank. A longtime star in Minnesota (3 Pro Bowls, 2017 First-Team All-Pro), Rhodes fell off the map in 2019 with an abysmal 2019 season in which he allowed a career-high 127.8 passer rating at 29 years old. The Colts took a chance on Rhodes with a one-year deal, and he delivered, posting a career-best 77.5 PFF coverage grade as he allowed solid numbers of 6.8 yards per target and 0.88 yards per cover snap. He's a restricted free agent, but 28-year-old Darious Williams has been an impressive late bloomer for the Rams. A 25-year-old rookie in 2018, Williams showed bright flashes over a small sample in 2019 and maintained that level of production after being promoted to a featured role in 2020. After posting a 78.9 overall PFF grade over 221 defensive snaps in 2019, Williams improved to a mark of 80.0 over 824 snaps in 2020, the fifth-best grade among cornerbacks to play at least 500 snaps. Williams has a superb nose for the ball, collecting 20 passes defended over just 94 career regular season and playoff targets, a rate of 21.3% that more than doubles the 2020 positional average of 10.2%. Williams has yielded three touchdowns against seven interceptions in his career, including the playoffs. At 29 years old, Williams' Rams teammate Troy Hill also had a strong 2020 season, posting a 75.7 PFF coverage grade that placed 17th out of 129 qualifiers. He thrived in the slot, allowing a 75.8 passer rating in slot coverage that ranked second-best among the 33 cornerbacks with at least 150 slot coverage snaps. Some of these veterans will maintain their late-career surges, but many will fall straight back down to earth. Joe Douglas and the Jets will need to remain cautious when browsing the old-timers on the cornerback market. It will be crucial for them to narrow the list down to strong scheme fits - as they say, you can't teach an old dog new tricks. For this reason, Richard Sherman once again comes to the forefront as an option that makes a lot of sense. If given the chance to remain in the Robert Saleh scheme where he thrived over the past two seasons, who is to say that he can't squeeze out one more solid season? How Douglas, Saleh, Jeff Ulbrich and the Jets choose to approach this unique cornerback market - very deep with intriguing options but lacking any slam-dunk choices devoid of risk - will dictate a lot about how the team's offseason plays out.