College Football


The Stathead blog is now defunct and so, evidently, is the Pro Football Reference blog. I’m not too sure what “business decision” led to that action, but it does mean one of the more neutral and popular meeting grounds for football analytics folks is now gone. It also means that Joe Reader has even less of a chance of understanding any particular change in PFR. Chase Stuart of PFR is now posting on Chris Brown’s blog, Smart Football.

The author of the Armchair Analysis blog, Jeff Cross, has tweeted me telling me that a new play by play data set is available, which he says is larger than that of Brian Burke.

Early T formations, or not?

Currently the Wikipedia is claiming that Bernie Bierman of the University of Minnesota was a T formation aficionado

U Minnesota ran the T in the 1930s? Really?

I’ve been doing my best to confirm or deny that. I ordered a couple books..

No mention of Bernie's T in this book.

I've skimmed this book, and haven't seen any diagrams with the T or any long discussion of the T formation. There are a lot of unbalanced single wing diagrams, though.

I also wrote Coach Hugh Wyatt, who sent me two nice letters, both of which state that Coach Bierman was a true blue single wing guy. In his book, “Winning Football”, I have yet to find any mention of the T, and in Rick Moore’s “University of Minnesota Football Vault”, there is no mention of Bernie’s T either.

I suspect an overzealous Wikipedia editor had a hand in that one. Given that Bud Wilkinson was one of Bernie’s players, a biography of Bud Wilkinson could be checked to see if the T formation was really the University of Minnesota’s major weapon.

The value of a turnover is a topic addressed in The Hidden Game of Football, noting that the turnover value consists of the loss of value by the team that lost the ball and the gain of value  by the team that recovered the ball. To think in these terms, a scoring model is necessary, one that gives a value to field position. With such a model then, the value is

Turnover = Value gained by team with the ball + Value lost by team without the ball

In  the case of the classic models of THGF, that value is 4 points, and it is 4 points no matter what part of the field the ball is recovered.

That invariance is a product of the invariant slope of the scoring model. The model in THGF is linear, the derivative of a line is a constant, and the slopes, because this model doesn’t take into account any differences between teams, cancel. That’s not true in models such as the Markov chain model of Keith Goldner, the cubic fit to a “nearly linear” model of Aaron Schatz in 2003, and the college expected points model (he calls his model equivalent points, but it’s clearly the same thing as an expected points model)  of Bill Connelly on the site Football Study Hall. Interestingly, Bill’s model and Keith’s model have a quadratic appearance, which guarantees better than constant slope throughout their curves. Aaron’s cubic fit has a clear “better than constant” slope beyond the 50 yard line or so.

Formula with slopes exceeding a constant result  in turnover values that maximize at the end zones and minimize in the middle  of the field, giving plots that Aaron calls the “Happy Turnover Smile Time Hour”. As an example, this is the value of a turnover on first and  ten (ball lost at the LOS) for Keith Goldner’s model

First and ten turnover value from Keith Goldner’s Markov chain model

And this is the piece of code you can use to calculate this curve yourself.

Note also, the models of Bill Connelly and Keith have no negative expected points values. This is unlike the David Romer model and also unlike Brian Burke’s expected points model. I suspect this is a consequence of how drives are scored. Keith is pretty explicit about his extinction “events” for drives in his model, none of which inherit any subsequent scoring by the opposition. In contrast, Brian suggests that a drive for a team that stalls inherits some “responsibility” for points subsequently scored.

A 1st down on an opponent’s 20 is worth 3.7 EP. But a 1st down on an offense’s own 5 yd line (95 yards to the end zone) is worth -0.5 EP. The team on defense is actually more likely to eventually score next.

This is interesting because this “inherited responsibility” tends to linearize the data set except inside  the 10 yard line on either end. A pretty good approximation to the first and ten data of the Brian Burke link above can be had with a line that is valued 5 points at one end,  -1 points at the other. The value of the slope becomes 0.06 points, and the value of the turnover becomes 4 points in this linearization of the Advanced Football Stats model. The value of the touchdown is 7.0 points minus subsequent field position, which is often assumed to be 27 yards. That yields

27*0.06 – 1.0 = 1.62 – 1.0 = 0.62 points,  or approximately 6.4 points for a TD.

This would yield, for a “Brianized” new passer rating formula, a surplus yardage value for the touchdown of 1.4 points / 0.06 = 23.3 yards.

The plot is below:

Eyeball linearization of BB’s EP plots yield this simplified linear scoring model. The surplus value of a TD = 23.3 yards, and a turnover is valued 66.7 yards.

Update 9/29/2011: No matter how much I want to turn the turnover equation into a difference, it’s better represented as a sum. You add the value lost to the value gained.

Ron Vanderlinden is a defensive coach, who was with the Colorado Buffaloes national championship team, then spent time at Northwestern University, coaching for their 1995 Big 10 Champion, before moving on to coach linebackers for Joe Paterno’s Penn State Nittany Lions. In this book he describes the Eagle and Stack defenses, the Eagle being the 4-3 defensive scheme he learned and developed while at Colorado, the Stack being Ron’s term for a defensive scheme derived from Jimmy Johnson’s Miami 4-3. The defense he describes is thus a melding of  two schemes, one better suited for strong running teams (the Eagle) and another better suited for spread formation passing teams (the Stack). In this, there is an analogy between Tom Landry’s 4-3 inside and 4-3 outside formations, the melding of which led to the 4-3 flex.

In depth detail on a 4-3 defensive scheme, this book is highly recommended.

This book describes in depth a very successful college program and defense, and as befits a book that describes a whole coaching system, it begins with a certain set of drills, pursuit drills in the very first chapter. After describing drills it them proceeds to the player profiles required for the various positions in the Eagle. Once complete he then gets into the Eagle Defense (4 chapters), the Stack (4 chapters), fusions of the two (2 chapters), 3 chapters on positional technique, and then 3 chapters on special situations, such as goal line defense. As such, in the wealth of practical detail, the book resembles a college textbook, and has a level of difficulty akin to a sophomore organic chemistry text, or a junior level biochemistry text.

This is a good coaches book, and for the casual fan, it should be skimmed and used as a reference. There are discussions of schemes I’ve not seen before, such as Cover 7, or Cover 5:

2 safeties close to LOS aid in run defense. 2 deep strong side DBs cover 1/4 of field, while weak side DB covers 1/2. FS has TE (light blue) and post responsibilities.

The Stack defense, though generally an umbrella defense, more easily allowing 4 deep coverage, can easily be converted into a 4-4.

To note, Ron  has his own unique nomenclature for offensive gaps (1 for “A”, 3 for “B” and so on), one that makes the gap assignment align with the defensive technique. His use of 6, 7 and 9 technique I found confusing, but that’s because the standard technique assignments aren’t consistent once you get to tight ends (I would have thought them to be 6, 6i and 7 respectively, but consistency is just a hobgoblin of small minds)..

Follow

Get every new post delivered to your Inbox.

Join 245 other followers