The chart below summarizes in two squiggly lines a little bit of college football history. In fact, these lines capture a little bit of US history. So, what are they?
I call this the running margin. Essentially, you sum over time the point margin of every game a team has ever played. When a team is winning games their line points up, and vice versa. You've probably guessed at this point that these are the running margins for Army (red) and Navy (blue). Clearly something (actually, a lot of things) happened in the late 1960s and early 1970s: The Civil Rights movement, unlimited substitutions, a war in SE Asia, the end of conscription in the US military, the wishbone, OPEC and stagflation, scholarship limits, etc. This is not the place to break it down, but, in short, where military academies were once major players in the college football scene, now they are not.
This next chart is Navy's running margin against Army. While both programs took a nosedive four decades ago, Army dove faster. Since 1950, Navy has outscored the cadets by more than 500 points, with almost half of that coming in the last decade.
To say that Army and Navy have struggled through the last half century is not to say they don't excel in some areas. Most obviously (and recently), they run the ball. The chart below is total rushing yards since 2005. From the bottom is Texas Tech (green), Army (red), Oregon (yellow), and Navy (blue). In the last 8 years, Navy has rushed for almost 18 miles. Army has kept pace with Oregon over the last several years, which is impressive considering what Oregon has been doing in the running game.
Finally, penalty yards (same colors as above). I sleep a little bit better at night knowing that the future leaders of my national defense avoid committing penalties. Army and Navy have been penalized about half as much as Tech and Oregon.