We were pleased to bring you the first edition of the PFF Mailbag last week and this week we continue what we plan to be a regular feature going forward.
You've again supplied us with plenty of worthy questions and we've selected out a handful for our analysts to answer here. If these questions spur further wonderings or remind you of something you wanted to ask at some point in the past, please send an email to [email protected] and you may see it worked in to a future PFF Mailbag post.
We appreciate the opportunity to dive into the details with our readers, so ask away!
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I would like to understand more about your normalization process. I am familiar with the concept of normalization for the purpose of re-scaling, but I am confused how your process works with normalizing the number of plays in each facet by setting the average player in that facet to zero. – Mark W.
Neil Hornsby: We are not trying to do anything too complex here; just get a roughly equal distribution of grades for each facet of play with zero being “average”.
The best way to look at this is often to take an example. Let’s consider pass protection for an offensive lineman. In this facet of play, we don’t give positive grades, only negative. Each time a player gives up no pressure we give him a zero and leave it at that. If he gives up a hurry, hit, or sack, we give him a negative grade which is dependent on how quickly the pressure came and when in the game it arrived; a strip-sack in garbage time isn’t worth a game-winning hurry with seconds on the clock. However, if we added all these grades up, we’d then have everyone with a negative grade and no account would be taken of number of zeros a player had. It would be possible for a player having played two snaps and given up a hit and a pressure (say -2.0) to look better than another who gave up only three sacks (say -4.0) in a 500 passing plays. Therefore, we give every player a small positive grade for every passing snap they are in. This “normalization factor” is worked out in advance to make the average player zero (or close to zero).
A similar process takes place for each facet of play for each position, so, for example, the positive normalization factor for a tackle in pass protection is higher than a guard which is, in turn, higher than for a center.
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You guys have talked a lot about Barry Richardson dragging down the quality of the Chiefs’ line. Now that they’ve added Eric Winston, how do you think their line grades out compared to the rest of the league? – Matt Conner
Ben Stockwell: The addition of Winston immediately makes the Chiefs one of the best offensive lines in the league. In terms of an offensive line ranking, Winston not only upgrades a line that we ranked 16th in the 2011 season, it plugs their biggest weakness and also takes away one of the best players from our fifth-ranked offensive line from last season. It doesn’t solve all of their problems, but any time that you can replace arguably the worst right tackle in the league with arguably the best, well you can’t really make a bigger jump than that.
You can only really imagine where the Chiefs might be if they hadn’t made the hasty decision of cutting Jared Gaither during the middle of the year. A line of Gaither at left tackle, Winston at right tackle and shifting Branden Albert inside to his collegiate position of guard would be a fearsome group for the Chiefs' backfield duo of Jamaal Charles and Peyton Hillis to run behind. As it is, they don’t have Gaither anymore, but they’re not exactly short changed.
The biggest obstacle for the Chiefs to improve in 2012 will be getting more from there interior offensive line as run blockers. Winston really helps them on the edge–not only in upgrading their pass protection, but also helping them spring more runs off-tackle–but Jon Asamoah and Ryan Lilja really need to up their game as interior run blockers. It's just about all this line is missing now that they have made that big leap at right tackle.
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You say in your grading explanation that +2.0 grades are extremely rare. What are the typical plays that earn this highest level of grades? – Sean D.
Ben Stockwell: As you spotted, the +2.0 grades are extremely rare and the only position group that sees them with any degree of regularity are defensive linemen who receive them as a “composite grade” coming on plays where they make excellent plays either in run defense or during their pass rush to make a quick tackle for loss or sack while also forcing a fumble on the play which “boosts” their grade up toward the +2.0 region. In terms of the 2011 season, 12 4-3 defensive ends recorded multiple +2.0 grades with Jabaal Sheard of the Cleveland Browns and Cliff Avril of the Detroit Lions tying for our league lead.
These strip-sacks form the largest proportion of the +2.0 grades as typically for other position groups we reserve the highest of grades for exceptional plays, which are typically +1.5 graded, that come at a pivotal point during a game. So, for example, an outstanding run by a tailback breaking two or three tackles and breaking away for a score might be worth +1.5 in the first quarter of a game but if it is delivered in the crunch, late in the fourth quarter to swing the game it would receive a boost for being in a key game situation, taking the grade for that play up to +2.0. Continuing the example of tailbacks, LeGarrette Blount’s astonishing run against the Packers at Lambeau Field in Week 11 would be an example of a +2.0 play.
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I agree with the Jaguars decision to part ways with David Garrard, it's fair to say Blaine Gabbert's rookie season was a major disappointment. The Jags admittedly have a weak receiver group and an unspectacular offensive line, but Gabbert's shortcomings looked to be mostly about Gabbert. Am I wrong to be pessimistic about his future? Did you see positives in his play that I missed? – John Lazzara
Sam Monson: This season Blaine Gabbert earned the worst QB grade we have given over a season since we started analyzing fully in 2008. Gabbert's -49.9 was a long way adrift of the next worst mark, which was that of Matthew Stafford in 2009 (-30.9). I'm not sure I've seen a QB look as bad as Gabbert did as consistently as Gabbert did given his lofty draft status. Throws were inaccurate, late, coming on bad decisions, and often from a spooked QB in the pocket.
Gabbert seems to have been a product of looking the part of a franchise QB. He's 6'5, 234lbs, has a decent arm and is a pretty good athlete. He looks exactly how a prototype QB should look these days. The trouble is that he didn't live up to the standard set by Chase Daniel at Missouri–the QB he followed–in the same offense. Daniel is 6-foot (on a good day), and went undrafted, and has since been a career backup (largely to Drew Brees). If Daniel was built like Gabbert, where would he have been drafted? And if Gabbert was just six feet tall, where would he have been taken?
Gabbert barely even flashed talent as a rookie, and you were usually lucky to find a single throw in games that made you sit up and say “Oh, OK, that's why he was a first round pick”. The Jaguars, as you rightly point out, didn't exactly have the best supporting cast to help him out, but that doesn't come close to excusing the play that he put out there, and he is going to have to make some major strides in his first full offseason before he looks remotely viable as a starting quarterback in this league. If he doesn’t, then it will likely be Chad Henne under center in Jacksonville sooner rather than later.
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In Week 5, Jim Leonhard had a higher coverage grade than Darrelle Revis in spite of having inferior coverage statistics. How is this possible? – Vinny Brando
Ben Stockwell: First things first, the normalization factors for pass coverage are different for safeties than for cornerbacks. As a result, Leonhard’s +0.9 coverage grade is not directly comparable to Revis’ grade of +0.7. What those grades show, if they are compared, is that both players had above average games in coverage and really, if you wanted to directly compare them, the 0.2 differential is just splitting hairs. Also, in terms of coverage statistics, we only track the primary coverage, so for safeties these aren’t always indicative of the plays that they are “in coverage” for. A corner can take the primary coverage, but the safety's “secondary” coverage can also be graded positively or negatively without showing up in their stat line.
This “secondary” coverage (or “safety help”) is the key difference-maker in Leonhard’s grade for that game in coverage. Leonhard was downgraded for his primary coverage of Wes Welker (missing a tackle in coverage early in the game), but as the game progressed, he chipped in with some positive grades on a pair of coverage plays that don’t show up in the stat line. His forced fumble from Aaron Hernandez late in the first quarter also boosted his coverage grade.
It's important to note that our coverage grades are not just for a player’s “primary” coverage assignments. If, for example, a screen reaches the second level and a safety misses a tackle, that will be reflected in his grading as well. These extra opportunities for grading plays predominantly fall to safeties, which is why the stat line in coverage is, generally speaking, less telling for safeties than it is for corners.
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