This skill determines how good players are at taking freekicks, corners and penalties. Around 10% of the chanches in a game come from freekicks, corners and penalties and having a set pieces specialist in your team will help you score from these chanches. There is also the possibility of a long shot Special Event related to set pieces.
Most teams will carry only one Set Pieces specialist on their team, who is also good enough to make the team through their other abilities.
Contrary to all other skills, the set pieces skill does not count into a players TSI.