Or How I Learned to Stop Worrying and Love Game Theory.
Now that we have a new defensive coordinator who, if Pancakes is to be believed, is in love with the blitz I thought I would give my own two cents on why pressuring the quarterback is the single most important part of playing defense. I'm no specialist in defensive shells a la Matt, but bear with me and you'll see that there is a solid foundation for what I'm going to propose.
For the purposes of this post, I'm going to compare football, specifically defense to poker, specifically no-limit hold 'em. Stay with me - the comparison works. For all the image that poker has as a game of wild bluffs and douchebags wearing their sunglasses indoors, there is actually a fundamental theorem that tells you in simple terms what you need to do to be a good player. Sure, there's a bunch of underlying mathematical gobbledygook that explains it, but the premise is amazingly simple: get your opponents to make costly mistakes by paying cards differently than they would if they knew your hand. Note that the deviousness and misdirection is implicit in the theory. As I'll show you later on in the post, so is aggression.
The best poker player, then, is the one who is able to profit the most from his opponents' mistakes while losing the least from his own. Being a good poker player does not mean making no mistakes - it means that you make a mistake on purpose in order to get your opponent to make a more costly mistake.
There are two kinds of ways to get your opponents to make mistakes: you can have them put money in the pot with the worst hand or you can make them fold the best hand, giving you all the money in the pot. The first point is pretty obvious, but it's the implications of the second point that make no-limit hold 'em so powerful, and make the comparison to no-limit hold 'em so relevant.
The majority of poker games have fixed betting limits. No-limit hold 'em, on the other hand, allows players to bet as much as they'd like. Because of this, every player is basically risking their entire stack on every hand they play. The threat of losing one's entire stack is a the key part of the game. If you're playing in a $1-2$ fixed-limit game with a $200 stack, you might lose $15 in a big pot. But if you're playing in a $1-$2 no-limit game with that same $200 stack, you could lose the entire stack in a single hand. As you can see, a player who is correctly aggressive can constantly put his opponents at risk of losing their stack and can cause them to play much more conservatively (and therefore make mistakes by throwing better hands away).
Example: Let's assume for a moment that you are playing poker against someone you know pretty well. With one betting round (of four) left there's $100 dollars in the pot and you both have $400 left to bet. You don't know exactly what your opponent has, but you have an idea of the range of hands he's likely playing and you estimate that, if both players check the hand down (meaning no one bets anymore) and the hand were played to the end, you will win 50 percent of the time. Your average profit is basically zero because you'll win half the time and your opponent will win half the time. If you play the hand out this way 100 times, you will win $100 half the time and lose $100 the other half of the time, for a net profit of $0.00. Bogus!
On the other hand, you estimate that if you bet out at your opponent, say $100, regardless of your own hand, he will fold half the time and call half the time. If he folds, you win the current money in the pot. If he calls, you'll win half the time. Since you are betting out regardless of your own hand, you will be betting with the best hand some of the time and betting with the worst hand (i.e. bluffing) some of the time.
Your aggression has just turned a breakeven situation into a winning one! 50 percent of the time you'll win the existing pot ($100) and the other 50 percent of the time you'll split the the $300 in the pot ($100 already in, plus your $100 bet and his $100 call). If you played the hand out 100 times, instead of breaking even, your net profit is $.50: you win $50 50 times and $0 50 times. (50 +0)/100 = .5 Bonus!
That may not sound like a lot, and there are some assumptions in there, but it is a useful demontration of how aggression can be useful. Which brings us to football.
The goal of aggression in hold 'em is to get your opponents to make a mistake by throwing away a better hand. Sure, sometimes they'll have a monster and then you'll lose. But if you can get them to throw away a few marginal hands that are better than yours by bluffing correctly, you've gotten them to make a mistake, which is your goal all along.
The same goes for defense. Just as with a poker hand, a football defense has its strengths and weaknesses. And, just as aggression can turn your weaker hands into money winners, it can also be used to cover up a defense's weaknesses. If you have a weak secondary but are able to get consistent pressure on a quarterback, you'll see a lot more bad throws out there, leading to more interceptions and incompletions.
There are many different styles of poker play, but they can be categorized based on how many hands a person plays. Players who don't bet a lot (called passive) will generally call bets and hope their hand holds up, but won't bet on their own. This style tends to be unprofitable. I would equate this style with the way the Texans D played under Richard Smith - they didn't commit a lot of extra resources to pressuring the quarterback (i.e. played passively), which put undue pressure on the secondary. The problem with this style of play is that you give up a lot of opportunities (read time) while you are waiting for your pass-rushers to get to the qb, and in the short season that is the NFL, you don't have that many opportunities.
The other style of poker involves betting your hands (so it's called aggressive play). There are risks involved, since opponents can trap you when they have a strong hand (sort of like a screen pass) but, per my example above, overall aggression is the way to go. This is where the Texans need to be.
I know this is a long-winded way of explaining something that everyone probably already knows, but it's worth pointing out that in games like poker (and also football) aggression is not only exciting, it's also a winning strategy.
Maybe Richard Smith needs to go read up on his poker theory.
There's a few other thoughts I have pertaining to defense and game theory. If I feel up to it I might get around to posting them one day.