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:


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.