Xperteleven offers the possibility to prepare your team for how your opponent will play. If you think your opponent will play a 4-4-2 formation you will be able to choose to prepare your team for that by selecting that formation in a dropdown list on the tactics page. The tactical option will also be possible to save within the default tactics.
Remember, the underlying principle again is: rock-paper-scissors.
If both teams prepare correctly: no effect.
If only one of the teams outguesses the other, the right guessing coach has a big advantage and the wrong a disadvantage.
If both coaches guess wrong, neither has more advantage than the other. Possible advantages/disadvantages are levelled.
To explain this in more detail then lets take a look at the below example.