A Little Theory & A Lot Of Practice
It can be easy to make excuses for not playing team defense in Mixed Ultimate, especially in man-to-man set-ups. About half the people on the field you would never choose to mark up on/cover prior to the pull, the people you want to set up switches with may not be the closest people to you, and the person in the best position to help you might not be the obvious choice given the situation. However, with practice and communication, there's no reason why skills such as poaching, switching, and being heads-up in general can't be incorporated into a defense's repertoire.
Unfortunately, there are no strict rules for teaching these skills since the configuration of genders on the field is so unpredictable and ever-changing; also, a person's thinking will often have to shift from moment to moment between guarding one's person, guarding one's gender, and knowing when to help out regardless of gender. It can be a lot to process and therefore becomes more a function of being able to react dynamically, which is, in larger part, based on a person's/D-team's experiences. Therefore, while theoretical explanation can help foster understanding of the basics, honing the skills is best done via real or simulated game situations.
A LITTLE THEORY…
Low Risk/High Reward Poaching
One of the easier poaching strategies to master in Mixed is a woman poach in the lane off of the woman handler. Often times, this offensive position will stay behind or around the disc and so a poach will never be too far from putting a mark on. The biggest advantage to this poach is that, if done properly, she can cut off the in-cuts, which means that the downfield defenders can back a little, thus the out-cuts are also covered. Then when the disc goes to the woman handler, the downfield defense can adjust to covering the in-cuts since this is generally the more dangerous part of the field at that point. The challenge for the poacher is to position herself so that she can see where the cuts are coming in while also keeping track of where the thrower is looking. Sideline talk can help her be in the right place at the right time. This D can be especially effective given adverse weather conditions and can be a way to switch up the D from zone to man so that the offense doesn't get too comfortable with one particular look.
Prepare for Switching to Make the D's Job Easier
Switching can take several different directions in Mixed. Although there are times when there is switching between genders, it is usually out of momentary necessity (i.e. zone O to man D transition) and looks to be resolved as quickly as possible since those are probably not the match-ups you are hoping for. However, switching within a gender leads to more equitable match-ups, can be planned for, and can be used to make defense easier and help save your legs a bit.
Being able to prepare for switches with players of your own gender depends on how the offense sets up and how quickly they get going. If there are two people of your gender in the stack, one defender could cover the in-cut and one could cover the out-cut. If there are three people of your gender in the stack, you could set up an in/out/middle or an in/out/break (this one is great around the endzone where there is less field to cover on the force side and a break side throw could lead to an easy score). The thing to remember is that the genders are probably spaced out in different places in the stack and so you have to keep an eye on what all the cutters of your gender are doing and continue to communicate with your teammate(s) when your wo/men start making their moves.
Switches become slightly trickier when the offense is in a split or ho stack. With the split stack, unless two of your gender are set up on one side of the field (in which case you could set up in/out), preparing for switches probably isn't possible. And with ho stack, the spacing between offensive players is probably greater than with a straight stack so, again, unless two of one gender are next to each other to provide an in/out set up opportunity, switching could prove to be more trouble than it's worth (although it might be worth a try anyway to see for yourself—defensive points are the times to take chances). What it comes down to is being aware of where the genders are set-up, what opportunities for switching, if any, that provides, and then communicating intensions with your teammates.
Be Heads Up and Go Get It If You Can
One mentality that needs to be avoided in Mixed is the one where a defender thinks s/he should only go for a disc that is meant for someone of his/her own gender. If you are in a position to make a bid on a disc, do it. This means knowing where the disc is, where the intended pass is going, and gauging the risk of leaving your person relatively undefended (if the situation calls for it). Probably the most advantageous places on the field for one to be heads up are the front of the stack, last in the stack, and as the person clearing out of the lane. The first person in the stack can keep an eye out for the quick, straight pass up the middle; the last person has to be aware of the deep shot; the defender clearing out of the lane can see the next cut coming in and can intercept the pass to that cut if the timing is right. I've found that one of the more fun things about being a woman in Mixed Ultimate is being underestimated. Sometimes you can make that work for you and get your team turns in the process.
AND A LOT OF PRACTICE
Provide Opportunities for Collective Learning
Team D is all about knowing each other and working together and for that you mostly have to learn together. So your aim as a team should be to get your D exposed to as many different situations and conditions as possible. In terms of practice time, 10-pull or some variation of it is a great "drill" because it lets the defense work together more intensely than a simple scrimmage would. Controlled scrimmage, such as a game to 5 with play stoppage, can also be valuable for real-time pointing out of where people are and where they should be for more efficient and effective defense. Then of course it is also extremely important to try some of these things out on people who don't have the inside track to what you've been working on. Worthwhile pre-series tournaments, as many as you can get your team to, are imperative for D-team development. A brief huddle after certain D points where the line can discuss positives, negatives, and adjustments will help to increase their collective learning.
Communicate, Communicate, Communicate!
Team D isn't just about the 7 people on the field; it's also about the other 10–20 on the sideline. True team D gets them involved as well. It is at times impossible for a single defender to see everything s/he needs to see in order to play the best D and so having another member of your team in your ear from the sideline for the duration of the point is invaluable. From the line before the pull, a defender should pick an available teammate from the sideline to talk to him/her and it is that person's responsibility to follow the defender and let him/her know what is going on elsewhere on the field that would effect how one plays D (i.e. who has the disc, where the disc is, where the thrower is looking, where the cuts are going, etc.). Regardless of what kind of D you are playing, communication on the field and from the sideline is a must. The best communication comes from familiarity with each other's voices, which is why being vocally active in everything from a basic endzone drill to sideline encouragement helps make sure that communication comes more naturally and will be there when it matters most.
Having retired from figure-skating, Kris Kelly has found time to help create, build, and lead one of the most successful Mixed teams in the world: Boston's Slow White. As an aggressive defender and cutter, Kris spends here spare time getting surgery and dispensing copious amounts of nutritional/preparation knowledge. (Check out her presentation on tournament prep at this year's UCPC).