San Diego Chargers

In terms of picking winners, the system went 2-2, unable really to deal with tough underdogs such as the Chargers and Colts. It picked Philadelphia, which by traditional means was the most in favor of the home team, though that game was one foot from being a Chicago win. So it went 2-0 in the NFC and 0-2 in the AFC.

In this round the home teams are favored in all four contests, but by varying amounts compared to the spread.

The methodology of how we pick is given here. The 2018 worksheet is given here. And as an aside, Doug Farrar’s new football book is very very good and I recommend that hard core fans buy it.

In the worksheet below, the factor 0.66 is the logit of home field advantage as calculated by the logistic regression. That’s equivalent to a HFA of 4.9 points. The playoff HFA of 62.7% is equivalent to 3.8 points. So, if you prefer 3.8 or even 3, just subtract 1.1 points or 1.9 points from the points margin respectively. Just for yucks we calculated the Rams and Cowboys odds both with the 0.66 factor of the fitted formula and the 0.518 factor of actual results, the latter in parentheses.

Whether I stick with this new formula is up in the air. I have an older formula that is much the same but not inclined to generate 15 point advantages, a bit tamer, if you will. We’ll see. I don’t do this for a living, just for fun, and the methodology link above gives the old formula.

That said, the second round worksheets.

Second Round Playoff Odds
Home Team Visiting Team Score Diff Win Prob Est. Point Spread
New Orleans Saints Philadelphia Eagles 0.685 0.66 5.1
LA Rams Dallas Cowboys 0.48 (0.34) 0.62 (0.58) 3.6 (2.5)
Kansas City Chiefs Indianapolis Colts 2.067 0.89 15
New England Patriots LA Chargers 0.942 0.72 7.0

Update: decided to add the old formula predictions, and also use the measured HFA factor.


Second Round Playoff Odds Old Formula
Home Team Visiting Team Score Diff Win Prob Est. Point Spread
New Orleans Saints Philadelphia Eagles 0.546 0.63 4.0
LA Rams Dallas Cowboys 0.313 0.58 2.3
Kansas City Chiefs Indianapolis Colts 1.707 0.85 12.6
New England Patriots LA Chargers 0.42 0.60 3.1

I’ve been lucky recently. Bill Arnsparger’s book tends to cost closer to $100 than a penny, but an inexpensive copy appeared and I grabbed it (even the Kindle version is around fifty dollars). Compared to Homer Smith’s book, this is less a compendium of diagrams, concepts and ideas and more of a handbook on how to organize and play football defense. It is at times synoptic, at times terse, something of a densely annotated outline. Bill is fond of capital letters, acronyms, and motivational slogans. He also needs to learn to spell “Wilkinson”.



As a defensive handbook, it’s full of fronts, pass defenses, pithy comments, and a fair amount of defensive gold. He talks about which pass defenses should be paired together. He’s good at finding ones whose reads would be the same to a QB but whose collective actions would be quite different (Cover 2 with his Two man coverage, for example).

As befits a handbook, nothing is beyond the ken of the curious mind. It’s in the depth of the material where it can be daunting. It feels like those sophomore survey courses where the instructor tries to teach everything. Clearly, a lot of time and effort have been poured into the collection of material in the book to make it a cohesive and workable system.

His approach to the history of defenses is pretty original. He starts with the wide tackle six, and between what Jones and Wilkinson have said about the wide tackle six, what Jones and Wilkinson have said about four and five spoke contain, what Homer Smith said about the evolution of the 8 man line, and this delightful Rod Rusk quote from Doctor Z’s tome:

We had trouble with Atlanta’s one back. I was very tempted, but I didn’t have the guts, to line us up in an old fashioned wide-tackle, six-man line, an old 6-2 defense. It keeps going around and around in my head. You can do it with nickel people. The defensive ends are strong safeties, then you’ve got four linemen inside them, then the two inside linebackers are, well, inside linebackers. I still might do it. You might see a lot of people going back to old ideas next year.

Is this the time when the modern 4-2-5 was conceptualized? I’m really intrigued by this train of thought.

Later he points out that the wide tackle six, if you put one of the linebackers at the nose on the line, becomes a kind of seven-diamond.

Seven-diamond, as it stems from the wide tackle six. Pull the right tackle and replace him with a linebacker, and you get something incredibly similar to the later 46 defense.

Seven-diamond, as it stems from the wide tackle six. Pull the right tackle and replace him with a linebacker, and you get something incredibly similar to the later 46 defense.

And then talks about how similar this seven-diamond is to the 46 defense.

It's interesting that Bill spends most of his time re: the flex defense discussing the play of the offside (flexed) end.

It’s interesting that Bill spends most of his time re: the flex defense discussing the play of the offside (flexed) end.

Later, he talks about the Tom Landry flex defense, and rather than focusing on the tackle up on the line, he discusses a flex strong and the pursuit play of the weakside defensive end. He never outright says it, but considering that he later discusses the development of his 53 and over/under 4-3 and 3-4 defenses, it’s hard to lose the impression that the weak side end, often handling the weak side A gap in pursuit, was a factor in his later 3-4 setups. Did he see it as a step towards a 3-4? Was the weak side flexed end a poor man’s “3-4 linebacker”?

With the notes I’ve shown so far, I’m really only scraping the surface of this book. I get the feeling a good coach could, in many ways, start and end with this book, and not suffer very much. If you’re a fan, the book is expensive enough that you should wait for an inexpensive copy. A defensive coach might actually find reason to buy this one as an ebook, and keep it around.

This is going to be a mixed bag of a post, talking about anything that has caught my eye over the past couple weeks. The first thing I’ll note is that on the recommendation of Tom Gower (you need his Twitter feed), I’ve read Josh Katzowitz’s book: Sid Gillman: Father of the Passing Game.


I didn’t know much about Gillman as a young man, though the 1963 AFL Championship was part of a greatest games collection I read through as a teen. The book isn’t a primer on Gillman’s ideas. Instead, it was more a discussion of his life, the issues he faced growing up (it’s clear Sid felt his Judaism affected his marketability as a coach in the college ranks). Not everyone gets the same chances in life, but Sid was a pretty tough guy, in his own right, and clearly the passion he felt for the sport drove him to a lot of personal success.

Worth the read. Be sure to read Tom Gower’s review as well, which is excellent.

ESPN is dealing with the football off season by slowly releasing a list of the “20 Greatest NFL Coaches” ( does its 100 best players, for much the same reason). I’m pretty sure neither Gillman nor Don Coryell will be on the list. The problem, of course, lies in the difference between the notions of “greatest” and “most influential”. The influence of both these men is undeniable. However, the greatest success for both these coaches has come has part of their respective coaching (and player) trees: Al Davis and Ara Parseghian come to mind when thinking about Gillman, with Don having a direct influence on coaches such as Joe Gibbs, and Ernie Zampese. John Madden was a product of both schools, and folks such as Norv Turner and Mike Martz are clear disciples of the Coryell way of doing things. It’s easy to go on and on here.

What’s harder to see is the separation (or fusion) of Gillman’s and Coryell’s respective coaching trees. Don never coached under or played for Gillman. And when I raised the question on Twitter, Josh Katzowitz responded with these tweets:

Josh Katzowitz : @smartfootball @FoodNSnellville From what I gathered, not much of a connection. Some of Don’s staff used to watch Gillman’s practices, tho.

Josh Katzowitz ‏: @FoodNSnellville @smartfootball Coryell was pretty adament that he didn’t take much from Gillman. Tom Bass, who coached for both, agreed.

Coaching clinics were popular then, and Sid Gillman appeared from Josh’s bio to be a popular clinic speaker. I’m sure these two mixed and heard each other speak. But Coryell had a powerful Southern California connection in Coach John McKay of USC, and I’m not sure how much Coryell and Gillman truly interacted.

Pro Football Weekly is going away, and Mike Tanier has a nice great article discussing the causes of the demise. In the middle of the discussion, a reader who called himself Richie took it upon himself to start trashing “The Hidden Game of Football” (which factors in because Bob Carroll, a coauthor of THGF, was also a contributor to PFW). Richie seems to think, among other things, that everything THGF discussed was “obvious” and that Bill James invented all of football analytics wholesale by inventing baseball analytics. It’s these kinds of assertions I really want to discuss.

I think the issue of baseball analytics encompassing the whole of football analytics can easily be dismissed by pointing out the solitary nature of baseball and its stats, their lack of entanglement issues, and the lack of a notion of field position, in the football sense of the term. Since baseball doesn’t have any such thing, any stat featuring any kind of relationship of field position to anything, or any stat derived from models of relationships of field position to anything, cannot have been created in a baseball world.

Sad to say, that’s almost any football stat of merit.

On the notion of obvious, THGF was the granddaddy of the scoring model for the average fan. I’d suggest that scoring models are certainly not obvious, or else every article I have with that tag would have been written up and dismissed years ago. What is not so obvious is that scoring models have a dual nature, akin to that of quantum mechanical objects, and the kinds of logic one needs to best understand scoring models parallels that of the kinds of things a chemistry major might encounter in his junior year of university, in a physical chemistry class (physicists might run into these issues sooner).

Scoring models have a dual nature. They are both deterministic and statistical/probabilistic at the same time.

They are deterministic in that for a typical down, distance, to go, and with a specific play by play data set, you can calculate the odds of scoring down to a hundredth of a point. They are statistical in that they represent the sum of dozens or hundreds of unique events, all compressed into a single measurement. When divorced from the parent data set, the kinds of logic you must use to analyze the meanings of the models, and formulas derived from those models, must take into account the statistical nature of the model involved.

It’s not easy. Most analysts turns models and formulas into something more concrete than they really are.

And this is just one component of the THGF contribution. I haven’t even mentioned the algebraic breakdown of the NFL passer rating they introduced, which dominates discussion of the rating to this day. It’s so influential that to a first approximation, no one can get past it.

Just tell me: how did you get from the formulas shown here to the THGF formula? And if you didn’t figure it out yourself, then how can you claim it is obvious?

In my last post, I introduced ways to determine the risk of NFL trades, using Pro Football Reference’s average AV per draft slot metric to assess the relative risk of the trade. I wish to continue the work done in the first post, by also taking a look  at the Eli Manning trades, and also the Robert Griffin III trades.

Eli's debt will be paid off in 2 more years of his current level of play.
RG3 will have to have a Sonny Jurgenson-like career, all in Washington, to pay off the value of the picks used to select him.

In the Eli trade, the New York Giants assumed a ‘AV debt’ comparable to that of Michael Vick, and a relative risk approximately the same as Michael Vick or Julio Jones. Looking, Eli has  rolled up perhaps 87 AV at this point, netting 12-15 AV a year. So, in two years, in purely AV terms, this trade would be even. Please note  that NFL championships appear to not net any AV, so if the value of the trade is measured in championships instead, I’d assume the New York Giants would consider themselves the outright winners of this trade.

The appropriate comparison with the Robert Griffin III trade is actually the Earl Campbell trade. The risk ratio is about the same, assuming the Washington Redskins go 8-8 and 9-7 the next two years, and end up with the #16 pick in 2013, and  the #20 pick in 2014. The lowest  value the AV Given column could total is 106, if the Washington Redskins ended up with the #31 pick twice. In any event, the Redskins are betting that RG3 will have a Sonny Jurgenson-esque career, and not just his Washington Redskin career, but his Eagles and Redskins career, in order to pay back the ‘AV debt’ that has been accrued by this trade.