3-5-2 is a rock formation which is good against 5-4-1 and 4-2-3-1.
This formation has a higher win rate against paper formations than 3-4-3.
It also has a slightly higher tie rate (0:0 or 1:1).
3-5-2 is best played with many crossing and header specialists. You can have up to 4 headers and up to 4 crossing specialists in this formation. Top teams place high bonus superstitious specialists on the remaining DM positions plus a cat in the goal. This gains a 85% win propability against 5-4-1 or 4-2-3-1 of equal strength.
Note though, that if you face an opponent with more than 15 less strength (and/or morale or specialist equivalent), you should consider to play an offensive scissors formation against counter formations anyway, and not a rock formation.