Switching on defense

Switching screens on defense is quickly becoming one of the most popular tactics in the NBA. The rise of “small ball” and spread pick’n’roll-based offense has led to rosters designed to be able to switch screens across multiple positions and emphasize keeping people in front of the ball. The previous defensive trends were built around Tom Thibodeau’s “strong side zone” which emphasized playing three over two on the pick’n’roll and then recovering to shooters later after forcing a difficult pass. That died when teams began to design their rosters to include three point shooting at every position.

Now it’s hard to do better than having long players at every position who can stay in front of shooters and deny easy looks while switching screens and avoiding dramatic mismatches. Teams that still rely on loading up with zone D tend to get buried by the better shooting teams that dominate the playoffs.

In college football, defense has long been defined by something akin to switching, which is to play “pattern-matching” coverages designed to allow defenders to stay in their respective areas of responsibility on the field and to keep receivers in front of them rather than overly worrying about maintaining matchups.

For instance, Nick Saban’s ubiquitous “mable” coverage for playing cover 3 against a trips formation. In this coverage, Alabama drops a safety down over a slot receiver to keep the LBs in the box and then players basically defend routes on the strong side with man coverage techniques based on whether they distribute into their zone of responsibility. On the backside they play man coverage.

The result of these styles of defense is to build different ways to allow the defense to maintain most of their matchups and be able to outnumber the more dangerous routes with “two over one” concepts. Someone somewhere in any pattern-matching concept is going to have to be able to hold up mano a mano but the more types of coverages the team has, the more flexible they can be with who has to hold up in isolation.

The rules of the game

Pattern-matching coverages tend to be built off of basic counting and geometry. Each coverage has a rule for defenders such as (for cornerbacks in the “mable” coverage above) “drop deep, play WR no. 1 (from the sideline) on any vertical and if he’s not vertical play on no. 2.” The rules ensure that the same guys “match” the route patterns that fall under their normal jurisdiction in a traditional zone coverage.

LBs tend to relate to receivers no. 3 and 4 from the sideline, which means that they focus on what the RBs and TEs are doing. That’s helpful because on any running play those same offensive players are going to serve as their keys. The safeties tend to have a wide range of responsibilities, particularly if a team has a deep playbook of both single-high and two-high pattern-matching coverages. In the two-high, quarters coverages there may be assignments in which they are playing over the top or fitting the run in the box while the single-high, cover 3 schemes might have them playing man coverage underneath.

Then there are teams that tend to zero in on one style or the other, most famously the Pat Narduzzi Michigan State Spartans and Pittsburgh Panthers. Narduzzi preferred to carry multiple versions of quarters coverages with a few minor differences between them that allowed the defense to have a few options for where to send help. For the most part though they developed players into specialists within the roles that their pattern-matching coverages created. They aggressively challenged opponents with press coverage outside and blitzes mixed in, and because of their own simplicity they tended to elicit simple and predictable gameplans from opponents.

The Spartans’ stance was essentially, “sure, all of our defenses will be vulnerable to X. But we’ll all know it and we’ll practice against X all the time to make it as challenging as possible to exploit...come at me, bro!”

The alternative approach is the one by Nick Saban or Brent Venables, to carry a wide variety of coverages so that the defense can always shade help where it’s needed or feature whichever position on the roster happens to be particularly strong in a given year.

The trade-offs in pattern-matching

Even with pattern-matching, Saban’s Alabama has had to make increasing use of nickel and now even dime sub-packages in order to hold up when the opponent is in a spread set with some of their best receivers lined up across from weaker coverage defenders. Many spread offenses are built around the premise that the backers or safeties with areas of responsibility in the middle of the field are the best to throw against and they have passing schemes designed to make them think quickly or hold up while isolated. Then there are the RPOs which can tell some pattern-matching defenders to do two different things at the same time such as “fill the B gap!” and “match the TE/slot on that stick route!”

Every coverage has to balance the challenge of maintaining a good matchup or a double team on the best WR (who may be in a different spot from week to week or even down to down) and choosing whether to have late responders to the run and immediate help against quick RPO passes or immediate help against the run and then tacklers closing on the quick RPO passes.

The goal of pattern-matching, to keep guys in consistent areas of the field defending the same sorts of routes and spaces they spend practice on, is also frequently subverted by the machinations of spread teams, hybrids, and tricksters like Jim Harbaugh or Scott Frost. If the offense knows who’s going to be where on the field, they can still dictate matchups and then the defense is left to either sub-package their way to resilience and/or have extensive playbooks with pages and pages of alternate matching rules to allow them to get help where it’s needed. Even then, with motion or clever packaging the offense can still put them in unwinnable situations.

The response by Saban has been increasingly towards using the nickel and dime sub-packages to ensure that every receiver has a defender across from him who can realistically hang with them in man coverage underneath. Then the safeties can move around to provide extra support as needed either in deep coverage or in the box against the run, either assignment which can be suitable for bigger, tackling-oriented players like Ronnie Harrison. Saban figures late help coming behind his DL is going to yield less damage than late against athletes in space.

AT TCU, Gary Patterson started a pair of sub-200 pound coverage defenders at either safety spot to help free his LBs to remain in the box and to play aggressively against the run. He has regularly played cover 3 schemes in the last few years that put a pair of sturdy LB/S hybrids in the box while 5-10, 190 pounders like Nick Orr covered in space.

In either event, the trend is towards fielding increasing numbers of small and versatile defenders who can cover and tackle in space. Even to the point of playing de-facto or real dime personnel on the majority of downs. Alabama’s nickel package included the lithe and very coverage savvy Rashaan Evans at “money” backer while TCU trusted in the 6-0, 210 pound Travin Howard in a similar position.

The challenge moving forward for these programs is going to be as offenses continue to invert the skill players and where they tend to align. For instance, when Oklahoma uses a big flex TE in the slot they necessitate that the defense either double him or find someone big enough to check him one on one. Michigan regularly takes this a step further and flexes out their TEs on the outside, sometimes on the solo side of a trips formation, so defenses are particularly strained in working out whether they want to play by their normal “I’ll take no. 1, you take no. 2” pattern matching rules or if they revert to man coverage to ensure better matchups.

This has shown up most commonly with the use of bigger guys outside that can learn to catch back shoulder fades and force corners to either be 6-0 or better or else for the defense to double them. For instance, the 6-4 Simmie Cobbs Jr in last year’s opener against Ohio State. Throwing to him against man coverage by the smaller Ohio State cornerbacks was akin to having a flex TE isolated on the weak side.

Nowadays in recruiting or in the draft everyone is extolling the virtues of the taller CB who isn’t as vulnerable to these sorts of tactics because of his reach, but that’s only the beginnings of a solution. In the same way that the NBA is looking for skilled athletes that are 6’6” or better to play at almost every position, the eventual landing point for maintaining these defensive stratagems against matchup hunting attacks is to try and field athletes that are 6’0” or better and sturdily built at every single position in the defensive backfield. Then you can play pattern-matching coverages without being concerned that the offense can manipulate your rules to create untenable matchups.

Perhaps football can get a boost from basketball guards displaced by freaks like 6-10 point guard Ben Simmons, or perhaps defenses will have to move on to the next strategic innovation to check offenses. Otherwise, they’ll be giving up open three pointers in the form of badly covered receivers running down the field.