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Last updated: 8th July 2021
Flex vs Vertical Stack
If the opponents create a tight vertical stack, you should surround the stack.
The 5 players guarding the stack are basically playing a 5v5 surrounding game. When an offensive player cuts out of the stack, a defender marks them tightly, and the other defenders communicate and reposition to account for the fact it’s now a 4v4 situation. This transition happens as soon as there is space between the offensive players, and the sandwiching/surrounding players in the 4v4 should continue to be ready to switch with the defender in the 1v1 – for example if the offensive player cuts deep for a few steps and then comes under, a defender towards the front of the stack should be prepared to switch onto the isolated cutter if appropriate.
At the front of the stack, the defender on the break side should be marking tight to the front, whereas the defender on the open side can take a few steps off. This prevents the quick pass to the break side, and puts the open side defender in a good position to mark whichever player cuts open side first.
The faster the defence can reposition after each cut, the less chance the offence has to exploit holes in the setup. Avoid having two defensive players mark one cutting player, as this creates an unbalanced sandwiching situation (e.g. 3v4), which is a weakness for the defence.
The players marking the stack can choose to split duties, for example from a 5v5 sandwich, into two sandwiches – 2v2 and 3v3. They might choose to do this in the case of a pre-existing imbalance, such as the offence having a few ‘superstar’ players, or when playing mixed gender ultimate.
As players clear out and rejoin the stack, the 1-to-1 defenders should rejoin the surrounding setup. As the number of players in the stack reduces, the surrounding defenders should tighten up – when there are only 2 players in the stack, the defenders should only be a couple of steps away from them, but when there are 5 players in the stack, the defenders can be five steps away.
Flex vs Horizontal Stack
Horizontal stack from the centre of the field has fairly good spacing, so an initial surrounding setup is not appropriate. Trying to have a deep & under poach when the disc is in the middle of the field leaves the offence with too much space, which they can use to split defenders and create separation. Defenders should start tight to their marks, and look for switches after the first cuts are made. The typical peppermill or diamond cutting patterns from horizontal stack have a weakness which can be exploited through proactive switching – more details on how to train players to spot these opportunities is in an $8 Training Tier video – the Conical Switching Drill.
If the disc is being brought into play from the sideline, the two deepest offensive players on the far side are so disconnected from the play that it is possible to bracket them effectively.
Flex vs Side Stack
Similar to marking vert stack, but use the sideline as your friend as the offence can’t cut in that direction. Advanced: nominate a deep poach who is looking to help out when an isolated cutter goes deep. The fact that the defenders have to cover 50% fewer angles from the stack means that the defence can afford to have one defender leaving the stack to stifle the space deep. This is not strictly part of Flex defence, but a specific poaching tactic which can be used effectively against side stacks. Communication and awareness of all the defenders on the field will have extra challenges when a deep poach is added, as when the stack breaks down the poaching defender needs to find their mark, and the defenders marking the stack are outnumbered.
Flex vs Stack in the endzone
When the opponents work the disc up the field against Flex and approach the end zone, often they will transition into a vertical stack to try to open up the space. Flexing defenders should automatically surround this stack as they would against a typical vertical stack offence, overloading the front slightly more than usual, stifling the space, and generating confusion & chaos.