Inspired by this thread from the Coach Huey X and O Board. Further, if you want to bone up on my specific definitions of concepts, check out this article.
Framing the Question:
"How much offense" and "How much passing" is a common question. I'll let others give their hard and fast answers. I think more interesting is how do you think about this question? Certainly over the course of many seasons one naturally may find out some equilibrium amount of offense, but most of our jobs do not have the security necessary to blindly experiment.
There are several questions you must ask when talking about "more or fewer" passing concepts.
1. How much will you put the ball in the air?
2. How many kinds of passing actions will you use?
3. How many concepts or schemes do you need under each?
How much do you want to put the ball in the air?
The first is the most important question. This is often a function of talent as much as anything else. To simplify, let's assume (I know unrealistically, but just for discussion) that you would always throw more if your talent could handle it. To me, the important question is not how good your receivers are. They are a concern, but more important by far is:
(a) how good are you at protecting your QB? (O-Line talent/technique)your ability to protect your QB (o-line), and
(b) Your QB's ability to read defenses and issues of accuracy, timing, and arm strength.
Thus, Receivers are a secondary question. Typically, if you can protect and have a good QB, receivers will take care of themselves. If you have gamebreakers on the outside but cannot handle much of the 5-step stuff, then you still can work to get the ball to them on screens, quicks, etc.
This is important because you do not want to practice and do not want to waste time installing what you won't run. So before you know "how much 5-step" or "how many concepts" you need to know how much you'll be putting the ball in the air, since the #1 rule of offense organizationis to not practice what you don't use and do practice what you do run, regardless of what you carry in your playbook.
How many kinds of passing actions will you use?
The second question is what kinds of passing actions. Are you a dropback team with draws and screens as your counters (Airraid/Texas Tech/Hal Mumme style), or more action passes, boots and sprint outs (spread teams, some run-oriented team), or maybe just a few pop passes and quicks from your veer sets. This depends on your types of talent and what will be your staple runs, etc. QB factors are key, like height, footspeed, comfortability out of the pocket, etc.
How many concepts or schemes do you need under each?
Finally, you've got some kind of rough breakdown of what will be your strengths. Week to week it will vary based on defense and opponents' weaknesses. (Since pre-season you look at your absolute abilities, but for a given opponent it is all about comparative advantages against your opponents. For example, you might be the worst running team in your district, but your opponent has an even worse rush defense and is geared for your pass, thus you beat them by running the ball. This little sidenote is too broad to explore here.) Anyway, over time this breakdown should correlate with what your strengths are. So let's say you're a 50% passing team, with about 40% of your passes being quick 3-step, 40% play action or sprint outs and bootlegs, and 20% 5-step passes. You can assume somewhere like 50 plays a game.
This means you're only going to throw 5-step passes about FIVE times a game (50% of your plays = 25, 20% of this = 5). You certainly don't need more than five 5-step concepts for a given game since you don't want to practice passes you won't run. More like you only need two or three at most.
This is important to help you frame your offense. The last few seasons I've thrown it around 25 times a game, with between 12-17 per game being 5-step straight dropback concepts (partially because my base play action are my same 5-step concepts). Since this is a big chunk of my offense and constituted an even bigger chunk of my yardage total I run more concepts than many, but these numbers still only justify six or so concepts. This still only leaves passes being run two or at most three times.
What about colleges and other passing teams?
It's helpful to think of the Airraid guys, they purportedly run about seven or eight, but really more like 12-15 concepts (often gloss over the basic concepts that they do run). Looking at Texas Tech with Mike Leach, who throws 55-60 times a game, still has a similar ratio of running each play 3-4 times. So by that math, about 3.5 pass attempts for every one pass concept, if you throw it 25 times you should only have SEVEN total passes, including boots, 3-step, and 5-step.
By that logic I run way too many concepts. So, the short answer if you're extrapolating from Texas Tech, less is probably more. The R&S guys have like five passes. Of course, each R&S package is like 4 or 5 plays; each Tech play is just one.
Conclusion
If you work backwards from your ability to protect and ability to throw, next to the types of throws that will work, then when you have a rough idea of how much you'll throw the ball and how many times you'll run boot and how many times you'll drop back for 5-step, you can then use a ratio of 2-3 attempts for every one pass play as a metric to give some guidance.
Note: The 2-3 times is over a season. For example if you play a Cover 2 team, you'll throw smash, 3-verticals, and double slants maybe 4 times each in a game and Curl/flat and all-hitch almost never. Then versus a Cover 1 and Cover 0 man and blitzing team, you'll run mesh 4-6 times that game, and then versus a zone team you'll only use it a few times. So it's not a hard and fast rule that you'll run each concept 2-3 times each game, just over time.
Further, this too is better suited to its own discussion, but the other concern when answering the question "How many pass concepts do I need?" is you need answers to everything you are likely to face. You typically need a Cover 3 beater, a Cover 2 beater, and a Cover 4 beater, some man beaters (2 and 1) and some anti-blitz (both screens and upfield "take-a-shot" passes).
Lastly, my two favorite pass plays are absolutely integral: draw and screen. Find any way you can to run them.
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ADDENDUM:
Right after posting I went to the Jerry Campbell football message board and came across this thread. Jerry Easton, Bill Mountjoy and others type out their response to the question "How much do you need in your passing game?" Since I gave the theoretical answer below, I figured I'd paste what Bill Mountjoy says he ACTUALLY does (at the High School level). Visit the thread (and contribute to the comments here or any of the two threads) if you want more.
BASE DROPBACK PASS SYSTEM:
PERSONNEL GROUPINGS = 2 TE/2 WR/1 RB, AND, 1 TE/3 WR/1 RB (both from 2x2 & 3x1 configurations):
1. 2 PASS PROTECTIONS at most (7 man pro = 3 free releases & 2 check releases; AND, 8 man pro = 2 free releases & 3 check releases) = a BASE/BOB type, & a TURNBACK type.
2. 3 THREE STEP dropback passes (I.E.: "HITCH"/"FADE"/"SLANT")
3. 5 FIVE STEP dropback passes (I.E.: "SMASH"/"CURL-FLAT"/"DOUBLE OUTS"/"POST"/"POST/CORNER")
4. "TAGS" off of the above for variety (can vary greatly as needed)
5. At least 1 SCREEN, & 1 DRAW.
6. Be able to handle: BLITZ-MAN/3 DEEP/2 DEEP (I KNOW there is more - but it all boils down to THIS).
7. QUALITY (execution) of the above = more important than MORE quantity!
8. SIMPLE READ CONCEPTS FOR QB (based upon "progressions of reveivers):
----A) INSIDE/OUT HORIZONTAL STRETCH (3 vs 2 or 2 vs 1) WORK 1/2 of field horizontally.
----B) OUTSIDE/IN HORIZIONTAL STRETCH (3 vs 2 or 2 vs 1) WORK 1/2 of field horizontally.
----C) LONG TO SHORT VERTICAL STRETCH (3 vs 2 or 2 vs 1) WORK 1/3 of field vertically.
----D) OBJECT RECEIVER READ (looking for a specific receiver for a specific reason).
9. PHILOSOPHY VS BLITZ IMPORTANT (BELOW):
A) Our philosophy vs the blitz are to call plays in one of two categories that are good vs. either:
1. BLITZ MAN, AND COVER 2 (MOFO), OR
2. BLITZ MAN, AND COVER 3 (MOFC).
B) WE DO NOT AUDIBLE TO DIFFERENT PROTECTIONS BECAUSE:
1. NEVER KNOW WHEN THEY ARE GOING TO COME (CAN BLUFF BLITZ & BACK OUT TO ZONE OR, THEY MAY COME).
2. QB NOT ALWAYS EQUIPPED TO SEE IT THE WAY YOU WANT HIM TO.
3. NOT ENOUGH GAME CLOCK TO AUDIBLE.
4. THEREFORE, WE NEED CALLS THAT ARE GOOD VS EVERYTHING.
5. USE 2 PLAY HUDDLE CALLS, OR “CHECK WITH ME AT THE LINE” – PLAYS THAT DO NOT CHANGE THE PROTECTION CALLED IN THE HUDDLE. THEY FIT INTO ONE OF THE CATEGORIES IN A) ABOVE.
C) AVOID “HOTS” BY USING 7 OR 8 MAN PROTECTION (BE SIMPLE ATTACKING BLITZ SO WE CAN SPEND MORE TIME ON GOOD FUNDAMENTALS – THIS LEADS TO BETTER EXECUTION). REASONS WE DON’T USE “HOT” RECEIVER(S):
1. QB DOESN’T SEE IT – HE GETS HIT!
2. QB SEES IT BUT RECEIVER DOESN’T!
D) MENTAL APPROACH VS BLITZ:
1. NOT “OH, NO – THEY’RE GOING TO BLITZ – I’M GOING TO GET HIT”, BUT:
2. “OH BOY” – IT’S A BLITZ – WE HAVE A CHANCE FOR A BIG PLAY”!!!
SUMMARY: “KISS” (KEEP IT SIMPLE – THE MORE EFFICIENT YOU ARE, THE MORE YOU MOVE THE CHAINS AND SCORE POINTS)!