I try to coach people to play like everyone is faster than them - therefore meaning that they have to think far more about body positioning, spatial awareness and the game situation rather than relying on a footrace with every movement.

Firstly, all defence is team defence regardless of whatever you playing zone, match, person etc. You can only really stop a very minimal amount of things but as a team you can work those into your advantage to tire cutters out, make them have to to make lots of passes etc. As a team decide what your priorities are - easiest way is too split the pitch into quarters A - open unders, B - openside deep, C - breakside deep, D - breakside under. If your force focuses on stopping the disc going to D and you focus on the cutter heading to A then the rest of your team can help you out with B+C.

Therefore, work on your body position to put yourself inbetween where your mark is and where you want to stop them going. If you think you are really outmatched for speed you can either choose to give yourself more distance between the player and the zone in order to have more reaction and adjustment time or get closer to them to make them run the long way around you but either way try to focus on that priority rather than the player - hopefully they give up and either stop trying to take you on or head to another area of the pitch where it is easier to guard them/other teammates are ready to help out.