Different players are suited to different playing positions. You can view a player's best positions by looking at the player’s details.
You can view the positions for which a player is best suited on the Player Details screen. In the graph, forwards are in red, midfielders in yellow, defenders in blue and goalkeepers are in green.
The brighter the positional area's shading, the better the player is at playing there. Use players in their best position to and they will receive bonus attribute points, called Tactical Bonus.
*If you're using the player on the pitch, the position he's currently playing in will blink.