People are both far stupider and smarter than one might think. Our brains are, on the whole, designed to pass tests, not write textbooks, which is why you can't necessarily explain step by step the chemistry of how a fire spreads from spark to gasoline to your house, but you definitely recognize the fact that your house is on fire, and that you should probably leave. (If you're really smart, you'll stop smoking meth in bed, but that is relatively advanced stuff for our species.)
Thus we're not all that bent about a writer admitting they're not much of an X's and O's guy as long as their instincts are reasonably right. The traditional canard slipped by a thousand athletes into any sports discussion is: "Did you play the game?" If yes, then say "You're still wrong;" if no, then say "Well there you go," and let the implied ("pussy") hang there at the end. This ignores basic facts even a rank novice can observe and point out to the player/coach in question: the quarterback twitching on the ground with a separated shoulder, the 28 point margin of defeat on the board, or the cornerback who gave up 278 yards in single coverage against a superior receiver.
In short: summarizing the effects and pivoting on that isn't that hard. However, there have to be bare minimums in the world. Spit it, Thomas Huxley:
To a person uninstructed in natural history, his country or sea-side stroll is a walk through a gallery filled with wonderful works of art, nine-tenths of which have their faces turned to the wall. Teach him something of natural history, and you place in his hands a catalogue of those which are worth turning around.
Ditto for football. The SEC Championship Game in 2008 was so much more enjoyable with an awareness of the formation game Dan Mullen played with Nick Saban's defense, and the 2009 game so much more frustrating for the lack of any adjustment or creativity by Florida's offensive staff. The role strategy plays can be overblown and overwhelmed by talent, but it is there, and it does matter. If you doubt this, ask any team Illinois has played for the past four years.
There should be--at the minimum--a basic understanding of the following.
1. The Rules. You don't have to be a lawyer, but at least be familiar with the basics. If you hear illegal formation, you should know why. If the clock's running, you should know why. The AFCA has a good catechism here. Positions should be an implied knowledge set here.
2. Offense. Okay, you don't have to bust down coaching trees, but you should know a few basics. You should know your I-formation, simple spread sets, and the option. Note: you don't necessarily have to know your flexbone from your Nebraska I from your wishbone (though that's always nice, and the professor appreciates the effort.) Just know the basic formations, plays, and how they work, and soon you'll start seeing the wrinkles and variations and all the fun geeky stuff pulled out in UFR and elsewhere. Wikipedia's got a solid set of basics hyah.
(Yes, they're bare-bones Mr. I-diagram-five-wide-sets-in-my-sleep, but what's there is the bare minimum. LIke illiteracy, sometimes the victims can get very far without knowing what you might assume are basics. Sometimes they can even coach large universities like Florida or Illinois.)
3. Defense. Basic fronts only, and that includes the nickel. A lowest common denominator would be the ability to a.) tell if a team is blitzing, and b.) watch the safeties and make a reasonable guess at the coverage. Zone/man is also mandatory stuff. The Wiki has short, tidy definitions of all of these.
4. Bare-bones Special Teams. Punting, when it happens, understanding kicker's ranges and yes, maybe the understanding of a few basic fakes. It's important for everyone because nothing, we repeat NOTHING lays bare the soul of a coach quite like his decisions regarding punting. It is the palm for the college football psychic to read to figure out the soul.
That would be our bare minimum that a writer would have to know, and that a fan should know about football rules. Chris has the definite AP course at Smart Football, but we understand: some of you just want to graduate and get to community college or that sweet job your uncle's getting you at the body shop. It shouldn't excuse not knowing the basics.