Coaches have systems that determine your team’s style of play. Coach cards also grant bonuses to players with skill sets that match the system. Selecting a coach will also select the system that your team will run. A coach’s gem level determines the bonus granted to the players and a player’s skill set determines their fit for the system. The better the player’s fit the more attributes will get a boost. You can change your coach or fine-tune your team in the coaching tab on the LINEUPS MANAGEMENT menu.