It is recommended you play around 2-3 and at max 5 protective players in a match unless your only focus is on defense and avoiding damage.

Try to place your protective players close by your strongest and/or most prone players with low resilience. Also take into account which areas of the field your opponent is trying to target with his brutal players.

Watch out for playing too many protectors if you are behind. Protectors focus on defense where you will get a bit stronger for each protector you have on the field, but it will also hurt your possession.

If you field more than 5 protectors you will lose A LOT of possession, but your defense will also get strong. So never do that unless your only focus is to try and park the bus and avoid your opponent will score.