It's a beautiful Saturday in May, and you're finally out on the field again after a bitterly grueling winter. During the halftime break of a tough game, you look over at the adjoining field. One of the teams seems to be comprised of old men, one of whom is ever so deliberately walking the disc in bounds. The disc is put in, and a backhand huck goes past a startled defense for the goal. "What's the score?" you ask of a participant. "Death or Glory 12-11, game to 13." "THAT'S DoG? But they look so ... old... they look so slow… they look so … terrible." You're intrigued, so you watch the next point. The defense ambles down but no one appears to be running very much. The sideline is yelling, "It's a zone! No, wait, it's a man. Hold on, it IS a zone. No, man. Oh my GoD, it's the Clam! Watch out!" But he's too late, for at that very moment, a defender poaches off to intercept a leading forehand pass in mid-stride, then tosses an easy floater for the game winner. You have just witnessed the Clam at its peak.

Why the Clam works is a mystery to many, even to those who use it regularly. As longtime Boston nemesis Jon Gewirtz astutely put it, the Clam "no longer intimidates or surprises good teams", but yet, it works. How? By creating confusion, and forcing the thrower to make split second decisions. In American football, the quarterback has only a few seconds to identify the defensive coverage, choose a receiver, determine whether the receiver is open, and deliver the ball, all with the looming threat of being pummeled by a large and fast behemoth of a defensive lineman. In ultimate, the thrower has up to ten seconds to make the pass, so most plays in ultimate develop much more slowly, and the receivers are typically open for a longer time, so most throwing decisions can be well thought out. The Clam attempts to make the wide open ultimate field look more like a crowded football field. Receivers will still break open, but only for an instant, thus forcing the thrower to recognize the situation and decide instantly.

Theoretically, there are always six potential receivers, but at any given moment, typically only one or two are viable threats, and these threats have a limited number of specific cuts available. The Clam attempts to systematically shut down the most likely and most threatening cuts, leaving open the low percentage passes and the short yardage passes. At its heart, it is a person to person defense, but which defender covers which offender isn't determined until after the cuts have started, and particular assignments are only valid as long as the offensive player is the most viable receiver in the defender's area. It's not unusual for one defender in the Clam to cover three different offensive players in a ten second stall count. It's also not unusual for a well-positioned defender not to cover anybody (and still be doing the job), since often players won't cut into an area where there is already a defender.

Many variants on the Clam exist, but all require teamwork to succeed. Conventional person to person defenses feature seven individual matchups. Virtually all teams implement some type of force on the mark, whether it is middle, sideline, forehand, or backhand. This is the first step toward reducing the area that each defender has to cover. With two players of comparable abilities, it is virtually impossible for the defense to prevent the offense from getting open. A cut is just a footrace to a particular spot on the field, except that the offensive player doesn't have to tell the defender what spot they are racing to or when the race starts, and can change his mind in the middle of the race. When part of the field is taken away by the marker or by the sideline, the defense doesn't have to worry about the whole field anymore, but that still leaves a lot of space to cover. The Clam goes one step farther by assigning a group of offensive players to a group of defensive players, with each defender looking for certain cuts to guard against. The defense positions its players so that for almost every race the offense wants to run, there is a defender already there who has a head start.

The simplest form of it is the "two person Clam", where the two defenders sandwich two offensive players. In Figure 1, offensive players O1 and O2 are in the stack waiting to cut, being covered by defenders A and B. Suppose that the only cuts available to O1 and O2 are hard cuts back to the disc for some reason (e.g., the disc is on the goal line, the offense never throws deep, the offense always starts the flow with a cut from the stack). Each defender is positioned in front of the cutters, one on each side. As soon as either O1 or O2 cuts, he is picked up by the nearer defender, and the remaining defender picks up the other offensive player, repositioning himself to take into account the force.

This concept can be extended to three or more players, each of whom is responsible for cuts in a particular direction. It is important that the defenders are "face-guarding" the offense, that is, facing their fronts, so they will be in front of whoever is cutting. The basic Clam has four defensive players sandwiching the last four offensive players in the stack, and the front players playing a more conventional man to man. For the sake of simplicity, the positions are referred to by number. The marker is called 0 and forces forehand, 1 and 2 play man to man on the first two players in the stack (usually the handlers), 3 (on the forehand side), 4 (on the backhand side) and 5 (in the middle) form a cup of sorts across the middle facing the stack, and 6 is the deepest player on the field and is responsible for all long passes (see Figure 2). (Aside: it should be noted here that "force forehand" really means "force right-handers forehand, force left-handers backhand", since most players are right-handed and you don't want to have the downfield mark switch depending on the thrower). In the primitive form (the "Clam for 1 (pass)"), players stay in their positions only long enough to pick up the first receiver that cuts into their area, then play their normal force forehand man to man.

Sidebar: Why force forehand?

When would you force backhand?

True mastery of the Clam requires the ability to stay in the Clam for several passes, the full point, if necessary. The players must be extremely comfortable with the concept of switching and playing position defense. In the full field Clam, 0, 1, and 2 always cover the three players closest to the disc, and whichever of them is closest is the marker while the other two are covering the handlers. If the receiver cuts away from the disc or cuts long, then 0/1/2 passes him off to 3 or 4 (depending on which side) and picks up the next available man. This rotation continues for as long as the Clam is being played. Many times, the Clam will shut down five cuts in the first eight seconds of the stall, but then 3 or 5 will get caught out of position and the offense will find the open receiver, and the offense simply fast breaks for the goal. When this happens, the defense must just accept that occasionally (critics say frequently) the Clam will look foolish and give up easy goals.

Figure 3 details one example of what might happen on a typical Clam point. The play begins with 3/4/5 all in tight against the stack, in order to hide the defense. Remember, one of the keys to success is surprise. As players cut from the middle or back of the stack, 3 and 4 flare out to pick them up, and 5 subtly shifts to that side in case another cut immediately follows, in which case he has to decide whether or not to cover that cut and leave the middle open. As passes get completed, the players reposition themselves to take into account the new disc location.

The Clam should be just one weapon used strategically as part of a full defensive arsenal. DoG's defensive strategist Billy Rodriguez explains that for a big game, he likes to start out playing the team's default defense, the force forehand man to man, for a few points until the offense gets into a rhythm, then he springs the Clam on them. Over the next few points, he'll mix in the zone, force backhand, and various "transition" defenses (in which the team changes defenses after a pre-determined number of passes) as well, until the offense is thinking more about what the defense is trying to do than about what they themselves should be doing. At that point, the battle is won, as throwers become unsure of who might be poaching, receivers become tentative and break off cuts, and the sideline gets frustrated by what appear to be stupid turnovers. In the videotape of the 1994 UPA Nationals, the veteran announcers can be heard labeling virtually every defense the Clam, regardless of whether DoG was playing the Clam, a zone, or straight man.

The Clam works best when it is unexpected. "The only defense that I will play indefinitely is the man to man," says Rodriguez. "Even if the Clam gets three turnovers in a row, I'll switch to man or zone." That way, the offense never has a chance to get comfortable and in the flow.

Some teams are more susceptible to the Clam than others. Young athletic teams tend to have more difficulty. These younger teams, especially those built around speed, rely on their ability to outrun the defense on the same type of comeback cut. If the defense refuses to allow itself to get into these races by employing the Clam or some other organized method of switching, the offense's preferred cuts are now covered. Against these teams, any non-standard defense is likely to find success, and Rodriguez recommends early and frequent use of the Clam.

First off, the team should be comfortable with the concept of switching. To many players, poaching is a sign of laziness, but limited, intelligent switching can have devastating effects. Begin to learn by practicing the two person Clam in a drill. Have a marker force forehand, station two offensive players in a stack about 15 yards away, put two defenders in a Clam, and allow only comeback cuts. This will help defenders learn to watch more than one thing at once.

Proper choice of personnel is also important to the success of the clam. 0-1-2 should be the tireless handler defenders, since they will be hanging out near the disc. If you will be playing the Clam for 1, the 0 position should be played by an excellent marker who can hold his ground. Strong marking is important, since a broken mark will often leave all the defenders poorly positioned and can result in an easy goal. 3-4-5 should be the veteran poachers who know how the offense cuts and who have experience in switching and poaching. 6 will be your agile big man who can cover a lot of ground and sky for the desperation huck.

It might be easier to institute the "Clam for 1" at first. Later, add the option to stay in it for 3 or 5 passes or even the whole point. DoG will decide on the line before the point (or on the sideline before the point, to get in the appropriate personnel) how many passes to play Clam for (if playing Clam), will usually let the sideline know, and will shout out a code word to remind the team to switch to force forehand. One final note is that in the event of a bad pull that doesn’t allow the defense time to set up, the Clam should be called off, so it is important that players also pay attention to whom they are lined up across from.

Patience is the key to unlocking the puzzle of the Clam. It's an aggressive, high-risk defense that tries to prey on bad decisions made quickly, so a well thought out and calm offense should be able to break it. The German national team frustrated Death or Glory at Worlds with their offense, and forced the Americans to change their whole strategy that game. With most teams' offense, the thrower has to wait for the cut to develop, and as a result, anybody (including the defense) who is watching can anticipate when the throw is coming. The Germans, though, would throw to an open space just as (or even before) the receiver was starting his move, and since the Clam defenders were trained to react to what the receivers were doing, they couldn't cover them, and the Germans moved the disc effortlessly. Eventually, DoG abandoned the Clam and the concept of face-guarding, and made its defenders play behind the receiver so as to get a view of both the receiver and the thrower.

The Clam will often break down when one of the defenders gets overloaded. Going back to the two person Clam example, if both offensive players cut at the same time to the same side of the field, the defender can usually only cover one of them and the other will be open. In a full Clam, since the defense has more time to see the offense's movements, they can adjust easier

The Clam was designed to counter offenses that have cuts that originate from a middle stack and come back to the disc, so most of the defenders are facing the cutters. Finland ran a side-stack offense at Worlds, so the Clam didn’t know how to position itself. Other teams have scored easily by throwing unexpected passes past unsuspecting defenders (another reason that the sideline must stay involved is to warn the defenders when a pass is thrown). Finally, since the Clam plays the percentages and encourages risky passes, a thrower with pinpoint accuracy on the long hammer or forehand huck can frequently shred the Clam.

Originally, the success of the Clam lay in its uniqueness. Since it was neither fully a man to man nor a zone, teams didn’t know how to react to it, and invariably made simple mistakes. As offenses adapted, the Clam added new wrinkles, and it will continue to change as more teams play it and add their own innovations. The premise behind it is simple: surround the enemy so that they always have to go through your team. And beating it seems easy enough: be patient, don't throw into poaches, and find the person who is temporarily uncovered. It sounds easy to beat.

But yet, it works.

Timeline:

1986: Boston's Mighty Popes introduce a variant of a 3-3-1 zone called the Clam.

1990: Earth Atomizer begins playing a one-pass man to man defense called the Clam.

1990-1991--Earth uses its secret defense in its struggle up the ladder, adding a highly effective end zone variant of it, causing Titanic and NYNY to rework their end zone offenses.

1993--The "Philly 8" by necessity invent the "Clam for the full point".

1994--The Clam becomes less of a gimmick and more of a basic philosophy with DoG as Boston wins its first national title in a decade. Confused announcers think everything is The Clam.

1995-1996--Thanks in part to the widespread popularity of the Internet, the Clam goes global.

It's not a man, it's not a zone, it's a MOAN.

Everyone's open, but there's no one to throw to.

Everywhere is open, but there’s no place to cut.

Why did you throw into that poach?

They’re not running.