Thoughts.

Legend goes that the original junk D was run by DoG or perhaps one of its predecessors with one Mr. Parinella and a skeleton crew numbering in the single digits–in order to conserve energy, they shirked away from man D (too much running) and zone D (too much running for the cup), opting for something a little more efficient–akin to a man D with well-coordinated switches. A little research shows that you can credit them for popularizing the D, but perhaps not the creation.

Above all else, it’s important to remember that any junk defense is NOT a true zone, and that players should almost never be just covering an area. Find a (wo)man and stick to ‘em until you find a new (bigger) threat to switch on to.

This is true to some extent of all zones (you want to avoid defensive tunnel vision), but it’s particularly important here (especially if you plan to run the junk set persistently rather than for only a few throws).

I’ll disclaim all of this by saying that this set is meant to be run against a straight stack; I’ll try to touch upon ways to do this with a ho-stack (Dartmouth developed one for natties last year and ran it with good success against Arizona for a couple points), but I don’t have a ton of insight to offer there–it’s harder to coordinate switches against spread defenses.

Personnel

Generally speaking (there are many variations–remember, this set’s strength is its flexibility):

• Three handler defenders (“0,1,2″–that’s “zero,” “one,” and “two.”). These guys basically wind up playing man defense on the three players closest to the disc (this likely will include whomever is first in the stack in a 2-handler set), but they don’t chase them terribly far downfield.

• Two open-side defenders (“3,4″). A clam set typically forces in one direction. Depending on the set, They’ll either be open-side ins, with one taking a wide cut to the sideline and one taking more of the “gut” cut straight to the disc, or one taking ins and one taking deeps.
• One “hammer stop” or break side guard (“5″). Again, pretty self explanatory. Generally this position looks to stop over the tops, but if you have a breakside deep this position can play in more and look to stop flat breaks to the front of the stack too.
• One deep/breakside deep (“6″). Pretty self-explanatory; either works with the open-side deep or is the deep with highest priority to stop deep shots (ie, plays deeper than the open-side deep).

Setup

The two most common clam variations I’ve seen run either a box or a diamond shape.

It’s worth noting that the shape is simply a guideline of where people are looking to cover–a clam set, at its finest, looks exactly like a man up until a player moves*. The 0-6 distinction refers to the fact that the clam set is a man D first, adds a bit of deception if any opposing sidelines are listening (sometimes we’ve loudly counted for a clam, hoping the receiving team would take the bait), and designates where players should ‘default’ to in a man-like setup, especially off of a stopped disc (OB pull or turnover or the like), with the 0-2 taking the first three and the 6 playing last back. It’s also good to have this guideline in case the O is running a set you don’t want to clam against–for instance, if they run a horizontal stack and you only run a clam against a straight stack.

That said, here are a couple diagrams for a ‘box’ style clam (also note the Ultimate Handbook has a [more] useful clam explanation with diagrams, too):

The first image shows a general clam setup off of a dead disc–the first three are more or less playing honest man D to start, while the back four have the directions they’re looking to pick up a switch in marked with arrows.

Note that the break-side defender is already cheating to the break side. Also note that she, more than any other position (except perhaps the deep), is playing more of a “zone” role, always on the lookout for passes into her area and feeling a little more freedom to pinch off to ensure the break side is well-covered.

Once players start to move you might see the clam respond like this. Players cutting in on the open side from deep will get picked up by the 3 or 4–having been poached off of, her cutter will likely head deep–where the 6 is waiting for her (or perhaps the 5, given the cut is on the break side). This is the clam in a…clamshell.

Should you choose to persist with the clam after the first throw/cuts, you might see the 2 switching onto the cutter in the lane if she moves for the dump, the 3 move to pressure a quick break up the middle…myriad adjustments can and must be made to accommodate cutter movement. A quick, dynamic offense can be hard to contain, but teams that are very systematic are easy pickings.

Other things to note:

Alternative setups I’ve seen involve using the third handler guard as a sort of cup-like upfield on the disc, or otherwise leveraging the flexibility of the three–perhaps man D in mid-field but cup-trapping on the sideline, etc. There is a TON of room for creativity with these sorts of sets (Harvard seemingly had a new junk or zone-ish look for us every time we met), so don’t be afraid to experiment and take some time thinking through how you might structure a junk set.

It’s not uncommon (at least, amongst my classmates during classwars–perhaps you won’t see it at nationals) to throw a junk set with no specifications–”do what feels right” in my circle, but I’ve heard the terms “zen zone” (where you are is where you should be) and “junkyard” used too. Relying on player savvy can be a powerful thing in the right situations–chaos, in appropriate quantity, will topple rigid order.

Goals

1. Confusion. Especially if this set goes off of a stopped disc (I’ve known teams to pull OB on purpose to ensure this), a sudden break from what looks like a normal man D to something that clearly is NOT a man D can create a window of confusion for enterprising defenders to capitalize on, especially against a team accustomed to you throwing man already (clam/junk sets are a GREAT halftime adjustment).
2. Dictating the offense’s pace. Again, with the confusion that a junk D creates, you’re almost guaranteed to stifle, if not stop entirely, the opponent’s set play. Zones dictate an offense’s pace as well, but they are more readable and quickly adjusted to–at its best, junk D is much harder to read the holes in and really makes THEM play to YOU.
3. Quick turns. As the clam’s primary strength is the element of surprise, this set is most likely to get the disc quickly. It’s very common to see a junk or clam set run for the first few throws to stop a set play and hopefully get a D, then returning to an honest man D before the offense can figure out how to beat it.
4. Sideline punishment. The clam is at its best on the (force) sideline, where the open-side defenders have an easier time denying their side of the field. Throwing this set starting on the sideline (off a turn mid-point for example) can be devastating, as the lack of space combines with confusion (#1) to force a tough decision (and hopefully #3).

Risks

All of the main risks associated with the typical clam revolve around the disc moving quickly from one side of the field to another:

1. Disc on the non-force sideline. Conversely to #4 in the goals, a disc all the way on the far side is very tough to defend–the open side becomes so expansive as to make effective coordination of switching a challenge at best. Typically if the disc gets this far over the offense is soon to find an upfield cutter, setting the wheels in motion for this set’s demise.

Control by: There are a couple ways to control for this. The first and easiest is to simply transition to man D. You might also consider switching the force at this juncture–it might backfire, however, if downfield (especially deep) defenders are far out of position. You could switch the force and maintain the clam if your players are versatile enough, but that takes a lot of practice and communication and might not be worth it in the big picture of this set’s purpose.

2. Quick breaks to midfield. Similar to the disc on the far side, this opens up a lot of space and renders several defenders out of position–a formula for quick shredding.
3. Long breaks to the far side. This enables #1.
4. Big break throws (cross-field hammers/blades for yards). These throws can kill your generic clam, for the same reasons as above.

Control by: Being diligent with your 3, 5, and third handler defender to take away the quick IO up the middle for #2, and with your 5 and potentially 6 for #3 and #4. You can also leverage the mark–shading to take away the quick inside break/long around, putting up a hand(s) against the hammer, etc.

As for the Horizontal Stack Clam…

…It’s a bit more difficult to run a good clam against a ho-stack simply because the cutters use more space and are more likely to be moving simultaneously–generally speaking I think we only ran this set for the first handful of passes, rather than persistently, as continued switching became too taxing (note, we had only practiced the set for about a week before using it).

The same general ideas apply vs. a ho as against a vert–switching to cover the open side threats, one to cover the open-side deep, one guy breakside hammer stop.

I think the real difference in running against a ho-stack, though, is how you leverage your handler defense.

Generally speaking, ho-stacks suck on the sideline, and generally speaking, clams become much more effective in the same position.

The idea, then, is to leverage your handler D–have them poach into the lane and encourage disc movement to the sideline–before applying an aggressive clam look. From the sideline the extra spacing of the cutters becomes less relevant, as the viable throwing lanes narrow, making it far easier to leverage the switching that a clam requires.

If a team refuses to make passes to the sideline, then you can maintain an extra upfield defender who can make open-side passes difficult, and (depending on how you choose to use the break-side handler defender) an upfield defender to discourage easy (around) break passes. Have your mark shade to take away inside-out passes and you can frustrate a horizontal stack.

You can leverage your handler guards in similar manner against a horizontal stack regardless of defensive set, by the way–if you’re not already doing so in man D, you’re putting yourself at the mercy of the other team’s O.

A clam is little more than coordinated poaching. This sort of action doesn’t have to happen purely within the confines of a junk “set,” but can (and should) occur naturally mid-point as the situation dictates. Strategically, think of the clam as a tool to free your players’ mindsets and encourage more awareness–develop their field sense, and encourage creative use in other situations.

*this is the sort of thing I’d love to rig up in a flash animation–hoping to get around to that over the next two weeks during my spring break.

UPDATE: You might also check out this thread on ultitalk for some regional differences in what a “clam” is. I’m talking about the American version.

Related posts:

1. Zone Sets: Transition Zones (and musings on others)
2. Zone Sets: How to Run a 3-2-2
3. Zone Sets: How to Run a 1-3-3
4. Zone Sets: How to Run a 4-person Cup, Courtesy of Gwen Ambler
5. Zone: Cup Fundamentals