I've written a lot about Win Probability Added in this space so far. In Week 5, I told you that Joe Flacco and Steve Smith led the NFL at their positions in WPA through four games. Both are still quite high though closer to where most would expect around 10th.
Three weeks ago, I told you that C.J. Mosley and Haloti Ngata led their positions in WPA. That still holds true. In order to make a defense of WPA to the stat skeptics out there, I pointed out that J.J. Watt not only leads all defensive ends in WPA, he has double the WPA of the second highest DE. WPA is doing something right and so are the other players on the lists.
Therefore, one name you might be surprised to see in the WPA conversation is Antoine Cason. He leads the NFL's cornerback corps. Cason was unceremoniously cut by Carolina during Carolina's imploding six-game losing streak where Baltimore eventually picked him up after their 84th defensive back went down with season ending injury.
Cason's WPA is almost surely buoyed primarily by his six pass deflections, four forced fumbles and two interceptions. Cason hasn't yet played a snap for the Ravens but now with a week on the team, and more importantly utter desperation at the position after yet more injuries, expect that to change.
Clarifying WPA's limitations
I've also been honest about what WPA does and doesn't do. One thing WPA does not do is capture a defender's bad plays. Get beat over the top for an 80 yard touchdown? Not reflected in WPA. It doesn't even capture the "good" plays if the play result still harms the team's chances. Jimmy Smith making a touchdown saving tackle against Cleveland in Week 3 after Elam got beat? Not reflected because the play itself helped Cleveland's chances to win (and there's no way to measure the "what-if" of if he had scored against the TD-saving tackle).
What WPA does do for defenders is capture the plays they make that result in their team becoming more likely to win. That is still tremendously useful.
It might be a stretch to equate WPA with "clutch" but it does the job better than most, including your personal subjective eye test.
With all that said, Antoine Cason is doing something right. Is he the best CB in the NFL? No, of course not. WPA doesn't capture the fact that quarterbacks avoid Richard Sherman like the plague. You need to be around the ball as a DB to have a chance to get WPA points. The best DBs are not necessarily WPA leaders because they obviously don't get the ball thrown their way much by design.
While Cason was on Carolina, he was surrounded by an incredibly disappointing defense. Cason was a part of that certainly and there were plenty of times where Cason was beat. But the fact remains that Carolina as a whole is just flat out horrible on defense. We may yet find out whether Cason can do better in ours.
Ravens don't need championship caliber secondary play - just "barely good enough" play
The Ravens are championship caliber at every position: pass game, run game, pass rush, run defense, special teams. All except the secondary. That's a devastating place to lack championship caliber talent. I would argue there is no greater weakness to have except quarterback. They are nearly at the point where receivers are going to have to suit up on defense like Julian Edelman did for New England in 2011. It's been that bad and we are that desperate.
But here's the truth of it: the Baltimore secondary doesn't need to be championship caliber. It just has to be good enough to get by. "Average" might even be enough as long as the rest of the team can make up the difference (and admittedly that's a big "if"). The Ravens cannot hope to get eight sacks a game in every game but they have enough everywhere else to have a chance of getting by with mediocre play from their secondary even against good teams.
Cason's play suggests he's at least capable of providing that if not perhaps a little more. He may not be the Corey Graham-esque savior of our depleted secondary but with a league best 1.22 WPA among cornerbacks, it is something.