Sunday, February 28, 2010

What Passer Rating Can Tell Us About Expected Wins

Somewhat surprisingly, quite a bit.

I started by considering how a team's passer rating was reflective of its performance. While it did seem to show a positive correlation (unsurprisingly) it really was only predictive within the context of a single team. In other words, a team passer rating of 80.0 could have been very good for some teams and very poor for others. It meant 13 win seasons for the Ravens and 8 win seasons for the Bills.

This is actually pretty useful as it can reveal outlying seasons. For example, in 2008 Green Bay won 6 games with a team passer rating of 93.3. As this was the worst win total by a team with a rating over 90 this decade (and probably ever) it was easy to predict a significant improvement in 2009, which we saw. Other measurements such as pythagorean win total supported this as well.

Once again, not very surprising.

But anyhow, the obvious thing to do at this point was look at the delta instead. What is the difference between a teams passer rating, and passer rating allowed?

The fit here is really tremendous.

Here's the ten year win total versus the ten year delta for each team:

Sorry for the fuzzy graph and huge gap in text. Excel --> Paint --> Blogger doesn't translate very well.

Anyhow, the fit appears to be very good. What interests me here is that the error bars appear to be logarithmic. Around the zero point there is a great deal of variance in win totals, however at the extremes the fit is much better. Granted, there are only a few datapoints at the extremes so this could easily be coincidence.

Perhaps the most interesting number from this graph is that Chicago managed a league-average 81 victories over the last 10 years despite having the third worst delta at -90.

Taking this a step further, here are is the full data from the ten year graph (318 datapoints):
This also demonstrates much of what we would already expect. The zero win Detroit Lions were really just an unlucky 2 win team. Most of the 1 win teams really should have landed more in the 4-5 win range. And so on.

But still, the scatter plot seems to be highly predictive, with a significant error bar. The trend line crosses the zero point right at 8 victories, exactly as we would expect.

So what does this mean? That passer rating delta can probably be very predictive in terms of regression. For example, in 2008 the Dolphins went from 1 win to 11. How much of the 11 wins were due to luck and how much due to a vast improvement in both passing and pass defense?

At -20 in 2007, Miami really was more like a 5 win team that got terribly unlucky. At +20 in 2008 was, in fact, exactly an 11 win team.

If we use those numbers as averages (and they do seem to be), then every 7 points in delta is equivalent to 1 victory in expectation. A team at +7 would be expected to win 9 games. A team at +14, 10. And so on.

There is also some evidence that this is no longer a linear relationship at the extremes, but since there are only a few extremes to look at it cannot really be determined whether this is so. Mostly though, from eyeballing the chart we see that teams with negative deltas tend to fall below the trendline while teams with positive deltas above.

Other notable outliers from the last couple of years: Carolina's 12 win season in 2008 in which they only had a +3 delta. They very predictably returned to average in 2009 at 8 wins and -1.2. We mentioned Green Bay in '08. They had a +21 delta and won 6 games. Their 11 wins in '09 were exactly in line, but there might be something going on with that team, considering their +33 in '09 should have been more like 13 wins. Washington underperformed their expectation in '09 with 4 wins and virtually no delta. Kansas City has a combined 10 victories the last 3 years where their expectation would have put them at 20.

I will probably continuing some of this over the next while as there is a lot of data to parse, however here's a first run at predicting victories in 2010. This is entirely based on recent trends based on PR delta and does not reflect coaching or personnel changes:

Denver 8
Miami 7
Indianapolis 11
New York Jets 7
Buffalo 8
New England 10
Tennessee 8
Baltimore 9
Pittsburgh 11
Jacksonville 8
Cincinnati 7
Cleveland 5
Oakland 6
Kansas City 6
Seattle 7
San Diego 10
New York Giants 8
Philadelphia 9
Washington 9
Dallas 10
Arizona 8
Minnesota 8
Tampa Bay 8
Green Bay 12
Detroit 3
Chicago 7
New Orleans 10
St. Louis 4
Carolina 8
San Francisco 7
Atlanta 7
Houston 8


Tuesday, February 23, 2010

The End Of A Wave?

With the Eagles releasing Brian Westbrook today we are seeing the final throes of what has been an amazing decade for running backs. Whether through luck, modern medicine, more creative offenses or (more likely) a combination, the first decade of the millennium has seen a surprisingly powerful core of runners who proved to be both productive and durable, the latter a particularly rare quality in NFL running backs.

13 running backs who joined the league from 1998 - 2004 have rushed for at least 6000 yards. Willis McGahee and Westbrook are all but certain to join that group this year. Four of those running backs (Freddie Taylor, Edgerrin James, Jamal Lewis and LaDanian Tomlinson) have rushed for over 10,000 with Clinton Portis (9696) and Thomas Jones (9217) likely to join them eventually, if not this year.

None of these guys will challenge the all-time rushing leaders but Tomlinson will finish in the top 10 with James, Taylor, Lewis and Portis likely finishing in the top 20. The wild card is Steven Jackson who has 6700 yards at age 26. Tomlinson is 26 rush TD behind Emmitt and has a narrow shot of finishing as the all-time record holder. Other than Alexander at 7th, the others again are further down the list.

To be honest, when I started this I thought I might have noticed something, but on reflection, maybe not. 1997 was a huge rookie year for running backs with 3 10,000 yarders (Dunn, Barber, Dillon) along with two more 6,000 yarders; Holmes and Antowain Smith. 1996 saw 10k Eddie George and 8k Stephen Davis. 1995 14k (!) Curtis Martin and 7k Terrell Davis. More recently the league has added Gore (5561) in '05, Jones-Drew (3924) in '06, Peterson (4484) in '07, and a number of promising backs (Johnson, Rice, Stewart, Mendenhall, Charles, others) in '08.

I guess it is more of a continuum than a blip.


Monday, February 8, 2010

The Manning Who [didn't] Choked Away the Superbowl

Today, the discussion in the media regarding the Manning INT is all about how great a read Tracy Porter made, and how Peyton Manning has [in some cases "yet again] blown it in the clutch in the big game. Throwing the INT on a late 4th quarter, game-tying (saving?) drive, is certainly damning evidence.

The problem is, it's surface perspective only, and doesn't tell you the real story...that Manning isn't at fault for that INT, and didn't choke this Superbowl away with that throw.

Disclaimer - I'm not an NFL coach, so realize that I have no true experience breaking down game tape or telling anyone the precise technical nature of the game. All I can do is tell you what I saw, upon repeated viewings, and what I believe based on what I saw.

Porter is getting a lot of credit for making a great play. But I'm not sure he's getting enough credit for how great it truly was. Manning is getting much of the blame for throwing the INT. I don't think he deserves any of it. If anyone on the Colts deserves any blame for the pick, it's Reggie Wayne.

I saw a great angle on one of ESPN/NFLN (I was flipping between the two for about two hours post-game last night) which showed what looked almost like a coach's tape view of the play...virtually the entire field was shown. This was a terrific angle, and I wish I'd grabbed it on TiVo to keep to watch more than the couple times I flipped back through it last night.

The timing of the three players is what's critical. After the snap, as Manning drops, Wayne begins what looks like a go route, headed straight up-field. Manning appears to be reading the whole left/center side of the field on drop-back. It looks to me as though he begins his throwing motion prior to Wayne breaking off and cutting in. At this point, Porter isn't breaking on the ball. Porter in fact looks to be back-pedalling, probably ready to pivot and run, giving Wayne cushion to run the route with him as there didn't appear to be much help over the top if Wayne broke straight.

As Manning is in throwing motion, Wayne stutters his feet. His strides get noticably shorter, PRIOR to his breaking off and cutting in. This looked to me to be the key to the play, because the moment this stutter begins, Porter plants to stop the back-pedal, and breaks on the ball. By the time Wayne has begun his cut, Porter has begun his break, Manning is letting the ball go...and the game has been decided.

Many of the defensive backs and wide receivers converted to analysts - Deion Sanders, John Lynch, Michael Irvin, etc - seem to be giving Porter the credit he deserves. I heard a few mentions of how much preparation plays into making a play like that. Many others have paid lip-service to how Manning blew it by throwing the critical interception that sealed the game. I've heard at least as many uses of the term "choke" for Manning as I've heard "preparation" for Porter.

To me, it's a shame. While Manning's had his share of "choke" moments in playoff games in the past, he actually played a very good game last night. I don't think he deserves the heat he's taken for that INT. His receivers actually cost him badly last night. Not just in Wayne's telegraphing the throw, but his drop of the 4th down attempt that could have pulled them within 7 to lead to an onsides kick with 44 seconds left, and Garcon's 3rd down drop in the second quarter, after which Manning only got 5 more possessions in over 40 minutes of game-time and were outscored 28-7.

Manning, to me, doesn't deserve the criticism he's receiving from the pick.


Tuesday, February 2, 2010

The Last Positions To Be Integrated

I was listening to sports radio this afternoon, the John Thompson Show, and they were interviewing Dwight Stephenson from the Super Bowl. Live from Radio Row in Ft. Lauderdale! Stephenson now owns a construction company in the area, and the group talked about local efforts to build some housing in blighted communities, a project Stephenson is active in.

Rich Walker mentions during the introduction, that it was not usual to be a center and be African-American in those years.
I hadn't been aware of that; and John Thompson hadn't been either. After a few minutes he circles back and asks why it was unusual to be an African-American, and play center. Stephenson discusses the "natural leadership" of the position: how it's a position of control, the huddle sets up around you, you lead the offense to the line of scrimmage, you make the blocking calls, etc. He states "Blacks didn't traditionally play that position."

Walker chimes in: "In football in general, it was pretty much an unwritten rule that you wouldn't play quarterback, center, middle linebacker, or free safety. You were never in the middle of it. So those were the last positions to be integrated."

I knew of the historical resistance to letting black players be quarterbacks. I'm not even sure we should call it "historical". Despite the successes of Warren Moon, Doug Williams, Randall Cunningham, and Donovan McNabb (among others), I think young black quarterbacks are still more likely to be shifted to safety when they get to college (or earlier!) than deployed at the QB position.

But I had not been aware that it extended to these other "leadership" positions up the middle of the offense and defense. Fascinating.

Podcast (9:50)
mp3 (4 mb)

Thompson asks his question at about 3:15, and Stephenson answers.
Walker's line about the last positions starts at about 5:05.

During his playing days in the 80s Stephenson was always described by the TV announcers as a great tactician at his position. I was intrigued to hear how he would sound. He comes across as an extremely classy, outgoing and bubbly guy. Energetic. Humble too: asked about his own playing career, he is careful to underscore his good fortune in teammates and coaches. He mentions Sylvester Croom. He also makes the case for Ray Donaldson to go to the Hall of Fame, starting at about 4:35. Donaldson was one of the last Baltimore Colts. Nice shout-out, Dwight.


Bill Belichick's Library

If you go to the New England Patriot's official bio sketch of Bill Belichick, and scroll to the bottom, you will find this:

The Belichick Library
Coach Belichick is an avid collector of football-related books, and along with his late father, Steve, amassed a library of more than 800 volumes. The library is believed to be one of the largest collection of football books in the world, behind the Pro Football Hall of Fame and the Library of Congress. In 2006, Coach Belichick moved his entire library to the Naval Academy, where his father coached for 33 years. The books are housed in a display at Ricketts Hall in Annapolis for future generations of football players, coaches and fans to enjoy.
I find that kind of awesome, in a variety of ways. First of all the notion that this guy, perceived as the most cerebral coach of his generation, has what is believed to be one of the largest collections of football books in the world. How cool is that? Second, the way this collection started:
Armen: You have your own library. How did that evolve? Is that an extension of what your father had given you?
Bill: Yes, I'd say pretty much. When I would go traveling with my dad, or when we would travel as a family, we would usually go and stop by used book stores or Salvation Army or something like that and check out the older books.
As Keteyian writes, "a father and son bound by family, football, and books."

And then, that the collection is housed at the Naval Academy! How cool is that?
Belichick Book Collection To Be Preserved At The Naval Academy
"My father and I often discussed consolidating our collections and making them available for others to enjoy," Belichick said. "Because of our ties to the Naval Academy and the Annapolis area, they will now have a perfect new home."
Belichick actively maintains his connection to Navy football – I know that when Paul Johnson used to coach there, Belichick would come down for Spring practice to watch them install their triple option. He was in Annapolis just a week ago.

Don't be shocked if he winds up coaching there, say 10 yrs down the line.

Presumably Belichick's library contains stuff like this:
While his New England Patriots use their bye week to regroup from Sunday's incredible 38-13 loss to the Miami Dolphins, this might be the perfect occasion for Belichick to get away and center himself. On a shelf somewhere in Ricketts Hall he likely will find "Winning Single Wing Football: A Simplified Guide for the Football Coach," written by Dr. Ken Keuffel, who played for Princeton in the 1940s. At the top of the book's cover is a testimonial:
The principles of single-wing football are enduring, and they're all covered by Ken Keuffel. Every coach in football can profit by reading this book. -- Bill Belichick

Another piece on the donation:
Belichick gives dad's books to Naval Academy
(full text requires purchase)


Monday, February 1, 2010

Sean Payton steals a good idea

From Bill Walsh!

Payton keeps Saints jovial with bellhop stunt.

Do you remember Walsh doing exactly the same thing, the week of the Niners first Super Bowl appearance after the 1981 season? Well Sean Payton does:

"We're always wanting to steal a pretty good idea. I think Bill Walsh, a long time ago, had a pretty good idea, and we just kind of took it like one of his offensive plays and ran with it."
That's probably the least of the things coaches take from Walsh. His book on how to build a football organization has been out of print for for a decade, yet coaches will pay hundreds of dollars for a used copy. (I wonder how many copies are in Bill Belichick's library?)

Like fashion, yesterday's discarded sports idea is tomorrow's unstoppable new wrinkle.


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