It's preseason, which means that my brain is in football mode but not in football shape. This is when it's time to start digging through harebrained theories and tearing them down until all of my hopes and dreams and optimism and football intelligence is reduced down to nothing so that it can be rebuilt again. Ooh-rah!

Let's get into the philosophies behind the 3-4 and 4-3 defenses. I mean, the real basics of it all.

4-3 Defense: Quite possibly the oldest and simplest defense in football. Obviously, there are different ways to run it, but it puts heavy emphasis on defensive linemen winning their battles and the secondary covering their assignments. Nobody has more responsibility, though, than the Middle Linebacker. He is required to be a jack-of-all-trades with elite speed and tackling ability.

Quite possibly the oldest and simplest defense in football. Obviously, there are different ways to run it, but it puts heavy emphasis on defensive linemen winning their battles and the secondary covering their assignments. Nobody has more responsibility, though, than the Middle Linebacker. He is required to be a jack-of-all-trades with elite speed and tackling ability. 3-4 Defense: Pretty much the opposite of above. There is no emphasis on defensive linemen winning their battles. In fact, their job is to try and stay in place. Talent in the secondary is not nearly as important as getting pressure on the QB. However, the responsibility of getting that pressure falls more on the scheme (and the coaching) than it does the actual players. The goal of the 3-4 is to confuse the offensive line so that they're not ready to block the 4th (or 5th or 6th) pass-rusher. The duties of the middle linebacker is quite literally shared by two, taking away the need for elite speed and the need for a jack-of-all-trades.

The 3-4 was the answer to the one-dimensional player. Got a guy that can rush the passer but he's too small to hold his ground against the run? We have a spot for him. What about a linebacker with elite tackling ability but no speed and no coverage skills? Sign him up. The 3-4 Defense was, and is, football's version of baseball's Moneyball. It's a system created to find value in the players that were commonly cast aside.

The problem was, and still is, that the 3-4 Defense takes responsibility out of the hands of the players and into the hands of the Defensive Coordinator. Here's where things gets really interesting …

I know this is oversimplification, but let's look at the Super Bowl winners of the last decade (when the 3-4 Defense has really exploded across the league). How many of them ran a 3-4 Defense? You have the Packers, Steelers and Patriots. They actually make up for 60% of the last 10 Super Bowl winners.

If you think about the 3-4 relying heavily on its coaching, it would make sense that those three teams were the ones that succeeded with the defense, in spite of their defensive inconsistencies. Bill Belichick (Patriots), Dick LeBeau (Steelers) and Dom Capers (Packers) are all amongst the Top 5 defensive minds in the NFL today. LeBeau and Belichick would both probably be included in an all-time Top 5 as well. In a defense that puts the emphasis and responsibility on the coaching, you need great coaching for great defense.

On the flip side of things, a 4-3 defense requires great talent at the Defensive End position to be great. Finding that talent can be difficult, but it can also cover up an incredible number of holes (Ex: Von Miller, Elvis Dumervil and the 2011 Denver Broncos). The more great DEs you can find, the less you need to worry about the rest of your team. One only needs to look at the reigning Super Bowl Champion New York Giants, who had a weak secondary and might've had Bob Costas play MLB for them in one of their playoff games, as an example of that.

Ever since the departure of Wade Phillips, the San Diego Chargers have struggled to retain a good Defensive Coordinator (we'll discuss this in a post later this week). The defensive coaching has fluctuated between poor and transitional, and the results have been predictable. A.J. Smith has tried to fix this by adding more defensive talent (Donald Butler, Eric Weddle, Antoine Cason, Larry English, etc.), but the responsibility of the defense still rests more in the hands of the coaching staff than it does the players as long as it remains a 3-4 scheme.

This is not intended to be a call for the team to switch from a predominantly 3-4 defense to a predominantly 4-3 defense this preseason, or even with the current coaching staff. It's mostly just thinking outloud. A switch at this point would put an unbelievable amount of pressure on players like Melvin Ingram, Donald Butler and Kendall Reyes. They would have to learn a new system, at the same time the defensive staff and the team veterans are learning it, while also adjusting to NFL game speed. There's almost no chance at success there.

This post's intention is to point out that the San Diego Chargers' most important 3-4 position has also been their most difficult one to fill. I'm not talking about the OLB spot that has been all but useless since Shawne Merriman's knee was shredded, or the SS spot that hasn't done much since Clinton Hart was getting freebies thrown his way. I'm talking about the Defensive Coordinator spot, which is far more important in a 3-4 than a 4-3. Maybe it's coming time to adapt instead of continuing to search for a fit.