Brutality is a huge part of the tactics in Futuball and can impact matches significantly. Hurting the opponents players will make them lose condition in the match and play at lower strength for the remaining match.
Playing with brutal players is a smart strategy if your opponent has weak protection and players with low resilience.
Playing brutal can also be a smart strategy if you are the underdog or behind and want damage your opponent and turn the edge to your advantage.
It is recommended to use from 0 to max 5 brutal players but it can vary depending on your opponents quality and their ability to protect well against on-pitch violence.
It is not recommended to use brutal players if you are the best team and your opponent is well protected.
Watch out for having brutal players in defense who targets your opponents attackers. it might be tempting - and also smart if successful - but it might also give your opponent more chances if your brutal attempts fails.
Playing brutal comes with a cost as your brutal player lose some focus on defending. So do not play too many brutal players at once, unless you are not afraid of your defense will stop all attacks.
The higher the brutality score of a player is the more effective he will naturally be. The same goes for protections score.