|Ultimate is a sport heavily slanted to the offense. A smart, accurate thrower and athletic receivers with good hands should score virtually every time. Fortunately for the defenders, at most levels, this is more a dream than a fact.
Still, we want to face the fact that the offense has the edge. Therefore, the defense's goal is not to shut the offense down, but to be on the spot to take advantage of miscues by the offense, and to force an occasional mistake.
Like all things, there are two parts to playing defense, tactical and strategic.
Tactical refers to the actual way you defend your man. This includes things like keeping hands low when marking, the simple decision to play in front of or behind your man, and so on.
Common defensive strategies which I don't like are the zone and the force.
I prefer playing straight-up defense. This means the marker in general is free to respond to the actions of the thrower. The hands should be kept spread and very low - throws go under or around arms, very rarely over. In addition, it is easier to bring your arms up fast than down. Watch the thrower's eyes and his grip on the disc as an indication of where he can throw, and listen to requests and advice from other defenders ("Watch left!") and respond if possible. Moving in crowds the thrower but allows him the chance to throw around you; moving out increases your chance of a hand block and does a better job of shutting down a progressively narrower section of the field. Mixing the two strategies up helps keep the thrower from getting used to your marking.
Other defenders should do the best they can - see below. One very valuable addition to the defensive arsenal is a byproduct of the empty V offense: when guarding a man watch for the passing lanes. It does not matter if he is wide open if there is no lane to get the pass to him. Be aware of lanes to other cutters as well. It is often possible to intercept a pass to cutters other than yours if you see where a pass might be going. Often I find that, rather than guarding the man, it is best to guard a position a meter or two in front of him. This way he may look open, but when the pass comes you can step into the lane and get to the pass first.
The interesting part, and the reason I enjoy defense more than I do offense, is the strategic. There is a lot to think about, and a lot that can be done.
The first and most important question is, how is the man you are guarding dangerous? Is he a long threat? Is he fast? Sneaky? If a handler, does he prefer to give-and-go, to swing, or to penetrate?
Second, how do you stack up to him physically? Are you faster? Quicker? Who has the reach advantage?
Third, how does your man fit into the offense? Not just what position is he playing, but how does he rate relatively in the offense? If a handler, do you want the disc in his hands more often, or in the other two handlers'? Would you rather try to force him in towards the disc, or out away from it? Is he a dangerous thrower, or a long thrower?
When you have the answer to these questions, you can start to decide how to play him. If he can and will go long, you either have to play behind him or arrange for help from someone deep who can play goalie. If he is not as good a handler, it may be best to play off him when he cuts in, conceding the short pass and getting the disc away from a more dangerous thrower.
Is it safe to cheat off him and try to help with others? Is he knowledgeable enough to use the opportunity if you do? Is he a key figure in his team's offense who they will look to often, or will he run around a lot pointlessly?
There is a further level to think about. Remember, the offense should complete passes. Therefore, if they do complete a pass it is not really a big deal. However, if as defender you knock down a pass that is a big deal. So, in some cases it is worthwhile to take chances, to try to lure the offense to throw to a man who looks open, when you are really waiting to pounce. In particular if you have an edge in quickness, this is a valuable tactic. Be cautious about doing this if you are guarding one of the main handlers, or are physically overmatched.
The value is even more than just the extra few turnovers you may create. Offense works best when it flows quickly. The thrower sees an opportunity and instantly responds to it. If you can get a couple of unexpected knockdowns the thrower starts to hesitate and look twice. This is worth more even than the turnovers that caused it.
It is vital to remember that defense is a team thing. If your man is covered but the other team scores the *defense* has been beaten, and the defense includes you. Look to help others - if a man is going long and has beaten his defender, call a switch and take the deep man. On a turnover, even before looking for "your man", look over your shoulder to see if there is a free man deep - if there is yell real loud, and unless there are 3 people nearer him than you, sprint back towards him.
Often someone guarding a non-handler can help out by functioning as a goalie. This means still guarding his man, but keeping an eye out for someone else heading long, and switching to pick him up. It sometimes helps to make this explicit - if someone is guarding a fast handler who might also go long, it can help the defender to know they can front him and concentrate on shutting down the short game, ceding the long pass because there is someone in back who will help.
Look to see what the offense wants to do and deny it - force them into a different offense. For instance, if they like to run a give-and-go, when a throw is made the mark should be sure his first 4 steps keep him between the former thrower and the disk, shutting down the return pass. If they want to swing someone should be sure to cut the swing off on an outlet to the middle This forces the offense out of their desired strategy and makes them improvise something different.
If you are near a passing lane keep your eyes open. Very often a pass may be thrown down the lane to someone else's man behind you. If you are aware of the lane you can be ready to jump into it and intercept the pass. As above, do this twice and you will seriously disrupt the offense's flow.
There are explicit team defensive strategies as well. One which we will use on occasion is a force. I know we all know forcing because we used it last week. In a force the marker blocks off a section of the field, so the defenders can shade their men to the other side.
Finally, remember defense relies on communication. Talk a lot - the deeps have a different perspective from the middles and the middles from the fronts. If your man gets free you can have a switch, but be sure to call it loud, and find the new man you are to cover. Call out when the disc is thrown; call out if you are in a position to help the marker; call out if you are having a good time. And, be sure to pass any observations or opinions you have to me and Jud so we can take them into account.
Since my hip operation my style of defense has changed completely. Before 2004 I could count on being among the fastest and quickest on the field. My style was to make my man look open, and be prepared to swoop in for the careless pass.
Since the operation I do not have the acceleration to do that, or the speed to beat my man to a spot. While before my goal was to make him look open even though he was covered, now it is the opposite: make him look covered even though he might be open. I play much more with my back to the disc, trying to stay in the sight line from the thrower to my man, so at a quick glance he will decide there is no throw. By not looking at the disc I lose the chance to anticipate its path, but can stick better step-by-step with the man I am covering.