Unlike the 1-3-2-1, the presence of a central midfielder in the 1-2-3-1 allows the system to have a player in the central channel to prevent direct counterattacks and serve as an anchor for spreading the ball around the field in attack. The 1-2-3-1 shares some of the challenges of the 1-3-2-1. Successful execution of the 1-2-3-1 requires mobility among the players. The 1-2-3-1 naturally creates triangles as in the 1-3-2-1. The outside midfielders are expected to move up and down the field, shifting from a 1-2-3-1 to a 1-4-1-1/1-3-2-1 to a 1-2-1-3 as the play progresses in different parts of the field. If one of the two backs is pulled wide, the other will slide central, ideally with the opposite side midfielder dropping in for balance.
The two backs are responsible for fronting the goalkeeper from left and right. The 1-2-3-1 flips the number of midfielders and backs from the 1-3-2-1. The space between the center mid and center back is also available to opponents. In this system, the central midfielder must be supported when outnumbered (for example, when facing a 1-3-2-1) – either by one of the forwards dropping into help (effectively creating a 1-3-2-1) or by the center back. If one of the wing players moves into this space, the back line players will need to rotate to cover. The 1-3-1-2 presents certain challenges – specifically in defending the wide areas of the field and defending in the central channel. The 1-3-1-2 supports mobility for the back wing players, allowing them to move into midfield and forward spaces to support an attack. The two forwards can potentially combine to outnumber a single center back in an opposing 3-back system. The 1-3-1-2 has the benefit of providing additional support up top and triangles between the forwards, midfielder, and backs. The 1-3-1-2 is a variation in which one of the midfielders is pushed forward with the remaining midfielder taking a central role. Likewise, the single center back can be outnumbered if the opponent overloads the center channel. The single striker can get isolated if they are not actively seeking out the game and can be shut down if doubled by the opponent. If the midfielders are not connected, and one is pulled wide, spaces can open up in the middle of the field that can be exploited. Depending on the positioning of the 2 midfielders, there are spaces wide that opponents can play through. The 1-3-2-1 also encourages mobility with spaces for players to move forward, laterally and backward within a style of play. A 1-3-2-1 naturally provides defensive support for each of the positions on the field through the presence of a line of players behind and at offsets. The 1-3-2-1 has the initial benefit of creating a series of triangles throughout the field, a desirable attribute for developing relationships in the game. The 1-3-2-1 introduces 3 lines – a backline of three, a midfield of two, and a striker.