July 2011

It’s a short book, very much an outline as much as it is anything, and that is both this book’s blessing and curse. It’s a blessing because it’s packed with ideas, and it’s something of a curse in that the details of implementation are often left up to the reader. For the fan, it’s perhaps an easier read than Ron Vanderlinden’s tome, and so I think much more suitable for the curious but casual fan of defensive technique.

For those who aren’t familiar with the double eagle flex, it’s worthwhile noting  that this is an 8 in the box defense closely related to the 46 employed by the Ryan family. There are 5 men along the line, including one flexed 3 technique tackle. The strong safety, or rover, is a hybrid player, and I’ve depicted him below as a linebacker. But much like many run oriented modern defenses, this player has to both play linebacker technique and also defend the pass.

It wouldn’t be a recent review on “Code and Football” if we didn’t provide the reader with a diagram, so this is my representation of the Double Eagle versus the Ace formation, three wide.

Ace formation versus double eagle flex. High School field. DBs funnel receivers into FS.

Note that both the boundary corner and the rover are supposed to funnel their men into the free safety.

The book is 98 pages long, packed with shifts, mods, stunts, all described in that  brief synoptic style.

From  the blog “Compete in All Things” comes  this nice little quote:

 The 3-4 has a lot of moving parts, more so than just about any other defense, and often has changing responsibilities with regards to force, contain, spill, all those terms we love to use to define good defense….


    The 3-4 is a seven man front to start. The actual front alignment varies quite a bit, with some teams preferring a 4-0-4 head up approach with slanting and stunting, and others preferring an ‘under’ front variation (9-5-1-3-5), and yet others running a 3-0-3 double eagle front

which, because I just think it’s cool, I’m going to illustrate:

3 different 34 fronts. The base front is on top, an over shifted front in the middle, and the double eagle front obtained by "Eagling" the DEs and ILBs (i.e. having them swap facing linemen) is on the bottom.

This dovetails  in with another neat quote, this time from Coach Huey’s board, on a thread devoted to what an Eagle defense is.

 “eagling” was often used to describe either the Okie tackle going in over the guard and the LB going out over the tackle, or in the 4-3 the end going out over the TE or over a ghost TE, and the OLB going in over the tackle…

To note as well, for all you 46 aficionados out there, Coach Huey has a seven nine page discussion of the 46 that’s been going on for almost four years now.

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)..

If you own exactly one book on the Dallas Cowboys, I’d strongly suggest this one be your book.

The essential oral narrative of the Dallas Cowboys.

Peter’s book is an oral narrative, composed of dozen of interviews of the “critical players”, and thus similar to, say, Studs Terkel’s “The Good War“. The book is organized in chronological order, from the foundation of the franchise to the middle 1990s. It’s not really a tell all book, though it interviews people who were very pro franchise and others who didn’t care much for their treatment (the linebacker Rodrigo Barnes, for example). It is rich in detail, exhaustive, but an easier read than its 838 pages would suggest. For the historian, comments about the way Tom Landry was blocking when the franchise began would be useful to those tracing the origins of the zone blocking scheme. We’ve talked about the specific quotes involved in our review of Pat Kirwan’s book.

Along with Pete’s book, I would also recommend this set of DVDs

along with this set of 10 Cowboys games.

These videos, along with the book, would aid any fan in tracing the nature and character of the franchise over the years. The one place where the book appears to be lacking is in any coverage of the Miami 4-3. While a ton of interviews touch on Tom Landry’s contribution to the 4-3 defense, such as the flex defense, coverage of Jimmy Johnson’s Miami 4-3 just isn’t there at all. That, I’d suggest, is the largest open hole in the Golenbock book.

This is the  third of a series on drawing football diagrams, and this time we’ll be talking about drawing the defensive side of the ball. For now, we’re going to have the offense going “up” the image and the defense going “down” the image. It’s easy enough to invert. Draw the offense the way we show in Part 2, rotate the result by 180 degrees, and then add your defensive players. In the old days, the defense was indicated with triangles. Most football bloggers, however, like to use fonts with names on them for the defense. The problem with fonts is that fonts are often tied to an operating system, so using them well requires some familiarity with font families. A good introduction to font families is here. And to note, Helvetica is installed as part of Image Magick, so if you want a no nonsense solution that should just work, set your font to “Helvetica-Bold”.

Since we are using Image Magick to generate our graphics, we can add color at will to our diagrams, and so one convention we’re going to follow for now is to use shape and color to distinguish offense from defense. offenses will be in white, defenses in yellow. Other conventions we could use are:

  • Using different shapes for linemen, linebackers, and defensive backs.
  • Tilting the defensive symbol to indicate a slanted lineman.
  • Shading the offensive lineman to indicate a shaded orientation on the  part of the defensive player.

For now, we’re going to use this image as the basis for our defenses. We’ve spoken about the Desert Swarm, a kind of double eagle defense, here.

Arizona versus Washington, 1992. I formation versus Desert Swarm. Whip (flex tackle) on TE side of formation..

And these are our attempts to duplicate that photograph. Obviously one corner and the free safety position are a product of speculation.

Defense in yellow, using symbols. Slant lineman denoted by tilt of triangles.

This graphic is a text based representation of the defense.

Helvetica-Bold is the font used here.

The images as displayed above are about 3/4 their actual size, so double click on them to see a full sized image (unless you’re using Chrome, in which case you’ll get a huge image).

Font notes:

To list the fonts that Image Magick can use by name, use the command (Win32/64 cmd window or Unix shell):

convert -list font | more

fonts that are not listed here can be accessed by direct path to the font file itself. In Ubuntu/Linux, the Fontmatrix utility can be a big help in seeing which fonts are good and determining the font path.

In this article, the example code is going to be given in Perl, using the Image::Magick module.

Code samples:

Previous parts of this article:

Anybody who says without qualification or categorization that “Eagles fans are scum” has never seriously read or listened to Ray Didinger. The book, “The Eagles Encyclopedia” is excellent, thorough, well researched, and better than any single book written about the history of a football team that I’ve read so far. And it does it by going about the subject in as many different ways as you can imagine, and with an acute eye for detail. There is a general history of the team. There is a section that highlights the important players on the team – guys like Steve Van Buren, Norm van Brocklin, Chuck Bednarik, Tommy McDonald, Tom Brookshier. There is a section for the coaches, especially valuable is the coverage of Earle (Greasy) Neale, but also including Buddy Ryan, Andy Reid and Dick Vermiel. They talk about every championship team  the Eagles have ever had. There is a section that talks about each and every playoff game for the team. The year to year details are stuck in the back, in an appendix.

Because the authors touch the team in multiple ways, you have the effect of many different lenses into the history of the Eagles. It makes them accessible, it shows sides of the team you might not have expected. The legendary Minnesota coach Bud Grant is an example: he spent some time playing for the Eagles, and he was good. He was just proud, and wanted to be paid in an era when players weren’t paid very much. So he left, to play for years in the CFL.

Back in the day, Bud Grant was an Eagle.

Roman Gabriel played for the Eagles for a while. That’s discussed in depth. The  two years that Herschel Walker played for the Eagles is discussed, Terrell Owens, and Jevon Kearse. Hugh Douglass, an underrated end, also comes to mind. Wilbert Montgomery, whom I saw play in his freshman year in the NAIA championship in Shreveport, has some excellent coverage.

The section on Bosh Pritchard caught my eye: he was a halfback who played alongside Steve Van Buren on the Earle Neale teams of the late 1940s. This Boss Pritchard quote is worth mentioning.

It’s such a different game now. Our tackles averaged 220 pounds. Today, they’ve got fullbacks who weigh 250.  These players work out with weights all  year. Our coaches wouldn’t let us lift weights. They said that weights made you muscle-bound. Of course, no one ever said that about me.

Not only is the “Eagles Encyclopedia” a good oversized hardback, you can get it for about 2 dollars on Amazon these days. It’s cheaper than a drug store paperback. And if there is any downside to the book, it ends in the 2004 season. So, it’s a few years behind the current state of the Eagles.

In the first part of this series, we talked about creating football fields, and provided code that would create fields whose hash marks were at high school width, college width, and pro field width. We provided the code as a Windows Batch file that used the command line tool Image Magick to do the actual graphics manipulation. In this part, we’ll talk about taking a field and drawing offenses onto the canvas.

Most offensive players are drawn by using circles (and was done so even in the days of Dana Bible). Since the fields we have drawn are colored a light green, for contrast we’ll want the circles filled in white and with black as the paint color. There may be other circles you might want drawn, ones shaded on one side with black, and perhaps you want the offense going down the field instead of up. We’re not going to worry about orientation finesses, as you can use any number of graphics tools to flip and rotate the image however you want. But we will talk about ways to make other kinds of images.

Defensive code setups, to some extent, are going to be OS specific. That’s because people like to use fonts, and the fonts on Windows aren’t entirely mirrored by the fonts in MacOS or Linux.

We’re also going to start introducing some Perl into the mix of code we show. This is because Perl’s ability to create functions and subroutines will actually simplify the task of creating a graphics code library, for those skilled enough to use the approach.


My recent explorations with the program Image Magick has left me thinking: since Image Magick is intended to be used in web sites, where people mass produce images (Image Magick can, for example, take a whole folder full of photos and generate thumbnail images), could I use Image Magick to create the outlines of football fields, complete with yardage lines and hash marks? And the answer so far is yes. Dimensions for football fields can be found here, on SportsKnowHow.com. The question then is translating those measurements into the dimensions of a regular screen size, such as 640 by 480 or 800 by 600. Please note that the American field is always 160 feet wide, so images whose width is divisible by 160 are desirable.

As an example of what can be done, I’ll show this image of a 46 defense versus a pro style offense on a pro style football field. Note that the image is displayed half of full size. Double click on the image to display full size.

46 defense from a 34 base, versus a pro style offense, pro hash marks.

All the diagram components have been placed with a set of three programs. The first generates three fields, one of pro, one of college and one of high school dimensions. The second places the offense on the field. The third handles the annotations of the defense.

A piece of the football field creation batch file.

A html-ised version of the batch file above is available here. Just cut and paste into a batch file on your local computer and correct variables as directed in the header.

So far I’m not using anything sophisticated to make these images, just batch files. I’m using batch because once I clean these up, I want to make them available to the Deuces and Coach Hoovers of this world for free. And to the high school coach who only has a Windows laptop or desktop, a batch file is the appropriate tool for automating something like this.

Remaining issues: are the hash marks given in the links above at the beginning of the distance from the sideline, at the middle of the distance from the sideline, or at the end of the distance from the sideline? I know it’s at most a 2 foot error, but I’d like to know. Likewise, does anyone know the best font for the numbers one might write on a football field? They’re 6 feet fall, 4 feet wide, and placed so the tip of the number is 9 feet deep into the field. Numbers aren’t essential at this point, just an aesthetic trick.

Update: It’s clear that in pro ball, there are vertical as well as horizontal hashmarks, and the horizontal ones are outside the vertical ones.

This is a quickie post, as I’ve been working on a talk for the Atlanta Perl Mongers tonight. The topic is Chart::Clicker, the graphics software that Cory Watson has written. A lot of the graphs seen on this site were made with Chart::Clicker, and after learning a few new tricks, I now have this new plot of my winning versus draft picks chart.

Winning and draft picks per year are correlated.

Since Chart::Clicker doesn’t have an obvious labeling tool (that I can discover), I used Image::Magick’s annotate command (links here and here) to post process the plot.

As John Reed points out , the phrase “Eagle” is abused, inconsistent, and overused. And even though Earle Neale’s “Eagle” defense is celebrated, it’s hard to know exactly what it is. Jene Bramel’s excellent series on pro defenses shows something akin to a 5-2-4 Oklahoma (father of the modern 34), but the diagram of Neale’s Eagle defense in Ryan and Walker’s 46 book (page 10) looks something more like this:

According to Ryan and Walker, Earle Neale's Eagle looked something like this.

This latter diagram is more believable, since people do claim that dropping the nose guard in Earle’s defense led to a kind of 4-3 (Or in Steve Belichick’s notation of the time, a 45 – back in the 1950s, corners would be sometimes be counted as linebacker depth players).

The three players in the middle – the diamond – are a 0 technique nose tackle, and two 3 technique tackles. The 3 technique tackles can also be called eagles – terminology used in odd front 4-3s and also certain derivatives of the 46. These sons of the 46 are often called double eagle defenses because of the 46 “diamond“, which they inherit from Buddy Ryan’s defense.

The most important of these defenses is called the Desert Swarm defense, made famous by Dick Tomey during his period as Arizona’s head coach. This defense lives on in college through the work of Rich Ellerson, currently the head coach at Army, who was a defensive staffer during Tomey’s run at Arizona. Though a number of sources call this defense a 4-3, it’s more an 8 in the box defense of the Ryan family, with the strong safety playing more of a linebacker technique, and the alignment to me looking quite a bit like a 5-3. To note, in the Desert Swarm, one of the 3 techniques (usually the weak side tackle) is a flexed tackle. Ironically, in the photo below, the flex tackle is on the strong side of the formation.

Literature on this defense is a little hard to come by. Some links that you might find useful are given below.

To summarize: a double eagle defense is one with a nose guard and 2 3 technique tackles. A double eagle flex has one flexed tackle. A double eagle double flex has two flexed tackles. Earle Neale’s Eagle appears to be a double eagle, though no one is 100% certain. These defenses should not be confused with the 34 Eagle of Fritz Schurmer, which is an eagle of an entirely different color.

Update: a more nuanced look at Fritz Schurmer’s Eagle can be found here.


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