Xs and Os on Saturday's Penn State-Michigan showdown from the proprietor of the essential Smart Football.

Defense and Penn State go together like Don Draper and pocket squares -- not only does it just look "right," it feels inevitable, as if this is how the world should be. When that team, wearing those uniforms, led by that coach, shuts down a hapless opponents under a sea of blitzes and gang tackles, "Linebacker U" speaks to something primordial.

Joe Paterno, of course, must get much of the credit for building his team in his tough, irascible image, but so should longtime defensive coordinator Jerry Sandusky. Sandusky, now retired, assembled those rugged 4-3 defenses over several decades, mutating it over multiple revolutions in offense, from option football back to I-formation running and west coast passing, and even into the early rumblings of the spread revolution in the late '90s. While talk of Paterno's eventual retirement continues to swirl, his longtime staff goes about the details of coaching players to excel. De facto defensive coordinator Tom Bradley (in one of its many traditions, Penn State does not actually name its coaches "offensive coordinator" or "defensive coordinator") and linebackers coach Ron Verlinden are among the very best and most knowledgable guys in the game, while anyone who has heard defensive line coach Larry Johnson speak will no doubt remember it for years afterward. Bradley in particular has kept Sandusky's great tradition intact, by keeping the framework that Penn State has used for decades while updating it for the newest waves of offensive evolution.

When you are assigned a position at Penn State, you are reminded of the ghosts that came before. Each linebacker has a position name to make sense of the defensive calls: Sam (strongside linebacker), and "Fritz" and "Backer." Penn State linebackers know which players, in the decades preceding them, were Fritzes and which were Backers. Similarly, in many systems the strong safety is known as a "monster" player because he plays all over the field. For PSU, the concept lives though Coach Rip Engle, who coached the Nittany Lions from 1950 to 1965, thought "monster" derogatory and thus called him "Hero" instead -- yet another tradition carried from from the age of Eisenhower to the present.

But once you peel back the layers you see the biggest holdover of them all for Penn State's defense: They are maybe the last, great "Cover 3" team -- i.e. their base coverage is a three-deep, four under zone defense. This is surprising because it eschews the fad coverage -- quarters, "Tampa Two," and even Cover 1 "robber," though they can use those if they like -- but also because Cover 3 is often seen as such a simple and, well, old coverage. But, like Draper's suits, while Penn State's defense might be a throwback, it works so damn well because they get all the little details right.

Fronts and coverages are tied together, which is the reason Bradley and Co. like it so much: They can get in an old-school eight-man front, and with a zone defense every defender has their eyes on the football. Contrast this with man defenses where members of the secondary might have their backs turned on option plays (deadly) or pass plays (can't see the ball in the air to make interceptions or breakups). On the front the Nittany Lions like the "over" and "under" fronts. The under front is what Pete Carroll (and Michigan, with some modifications) tends to base out of; the "over" front isn't as popular these days but essentially involves shifting the defensive line towards the tight-end and bringing the Sam linebacker to line up on the weak side. The coverage is quite literally three deep defenders with four underneath zone players -- hence "Cover 3."

The advantage here is that the defense gets to basically cover all of the offensive linemen while freeing up those ubiquitous All-Americans at linebacker to roam and make plays. Add to that the strong safety (or "hero") player playing short -- and a secondary focused on stopping the big play -- and you've got a very aggressive "team" defense that flows fast to the football. Indeed, one adjustment Bradley made against Michigan last year was to play with a true or "Miami" 4-3 look, with just four down linemen and the three linebackers off the ball reading the play. They were able to control Michigan's offensive line with their four down linemen, and the three linebackers just attacked the play downhill. Within the coverage, the secondary is also able to do an excellent job reading the offense's patterns. There are a lot of routes that are supposed to beat Cover 3, but very few get open against Penn State.

This is not to imply that this is all Penn State's defense does. The other biggest part of Penn State's defense is its robust zone-blitz package. JoePa's staff has a variety of blitzes, though they have a cardinal rule: Once a zone blitz is called, it will be run; no checking out of it at the last minute. One thing they believe strongly in is to avoid checking out of the blitz if the tight-end shifts or the offense goes in motion or the like, because they don't want half the defense doing one thing and the other half doing something else. The goal of any zone blitz is to confuse the quarterback's "hot" reads by dropping a linemen into the area vacated a blitzer, and to confuse the blocking scheme by overloading one area of the line, which isn't sure which linemen might be dropping off into coverage.

Note two key elements: One, the coverage remains very similar to above, a simple three-deep coverage. Now the underneath only involves three players, and note in particularly the defensive end to the tight-end side. He helps make the play go by stepping in as if to blitz before backing out. By doing so he controls an offensive lineman, and the "Hero," if he times it right, will likely be unblocked through the "B" gap, or the gap between the offensive guard and tackle.

Of course if you want to zone-blitz a solid spread running team like Michigan -- and admittedly, Bradley didn't call too many blitzes in '08, because he didn't need to -- you have to be sound against all the various run-game phases. This means that each blitz must be "option" sound. Before the snap Penn State's defenders must know who they're responsible for in case of an option: That mean they must identify the possible "pitch" players (in the diagram above, likely the slot receiver on a bubble screen) and who would take the quarterback. The option package off the zone read that Michigan runs is not as dangerous as it is from, say, Paul Johnson's flexbone, but that's also because the front side of the run play is the focus. Last year Michigan could get no movement up front with its line and its quarterbacks were no threat to run, and the Wolverines still managed over 200 yards rushing with savvy gameplanning out of the gate, before the Lions caught on and roared back (no pun intended) to an easy win over obviously inferior talent. This year, facing a vastly improved offensive line and a pair of much more athletic runners out of the shotgun, Penn State can't rely on simply overpowering the Wolverines late.

Michigan has done some more creative things with its H-backs and tight ends this year, particularly by bringing them across the formation to block on the backside. In this way they might mess up Penn State's perception of which side if Michigan's strength: Even if the tight end aligns to one side, because he might pull across the line, the strength might be to the other. But if the defense overshifts in expectation of the tight end/H-back pulling away from the strength, Michigan can just power straight away behind him. PSU will likely try to disrupt this by letting its linebackers do plenty of reading while allowing the defensive line to "stunt" and "slant" -- i.e. angle and attack in a particular direction to disrupt the blocking. Penn State almost always slants toward the tight end, but might adjust that if Michigan can find a successful counter. In any event, the onus will be on Michigan to improve this year compared to last.

Penn State's defense is both throwback and modern attack machine. The base, the calls, the position names, and, yes, the uniforms, all imply something old, something classic. But the details are as new as the players filling the roles. Indeed, they must be to counteract all the innovation offenses have presented over the years, like antibodies mutating in order to attack and destroy new strains of illness. And while Penn State's defensive staff is excellent -- and no doubt they receive much discretion -- at the center remains Joe Paterno, who weathered calls for his removal a few years back and continues to have his defense ready to play. Joe Pa, in his own strange way (and endless philandering excluded), is sort of the closest thing we have to a real-life football Don Draper: A throwback alpha male shaped by a modern lens. And, if that describes the man, it certainly describes his defense, which stylishly -- if brutally -- manages it all in their own classic wardrobe.

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Chris Brown writes the strategy and philosophy site Smart Football and also contributes to the New York Times' Fifth Down blog. You can reach him at chris at smartfootball.com, or follow him on Twitter.