The picture above is of a match being played between two teams i.e. Team Blue and Black.
The Team Black is playing with the formation 4-1-4-1 which is very useful while playing attacking football with a build-up. The Team Blue is playing with the formation of 4-3-3 with an offensive strategy.
The players of the Blue Team who are playing at the Left Back and Left Wing positions are very important in this formation, as they are always at the flanks and have to use this opportunity to move forward with the ball. These positions, especially the Left back position are very important. The likes of Roberto Carlos, Marcelo at Real Madrid are the stars of this position. The crosses played from the flanks help a lot in scoring goals.