4-2-3-1 was yesterday

The description of formations through rows of numbers are an ambiguous thing: on the one hand, they allow to be clearly defined in a simple manner, the spatial arrangement. On the other hand, simplify formations such number, the actual arrangement in the square.
Hardly a team that is situated in a 4-2-3-1 nominally operates permanently in this formation.
An example is the BVB. Commentators like to talk of "classic 4-2-3-1 system," when it comes to Klopp's team. In this case, this arrangement is usually available only on paper. The reason is the flexible part of Kagawa: In opposing ball possession, he is often found next to Lewandowski. Dortmund's famous notorious Pressing takes place so often in the 4-4-2.
In private possession Kagawa falls far behind, however, against Nuremberg over the weekend he was even to be found behind the sixes. Here, the arrangement in the central midfield is more like a 4-1-4-1 same. On paper, like the 4-2-3-1 vote - on the field, it is nonsense.
The FC Barcelona game and the fluid
The use of different systems in the defense and ball possession is not an invention of Jürgen Klopp. Smooth transitions between different game systems are fundamental in modern football. The FC Barcelona, the tactical role model for many teams, it's done: With the constant reshuffles and position changes, it is impossible to attribute a fixed formation. Sometimes they act in the 4-4-2, 3-5-2 in the situation in the next, often even without a real center forward.
By forcing the loose arrangement of the Barca players of their opponents to abandon their positions, which are free of gaps in the defensive order. Isolate in a time when the tactically disciplined teams with two lines of four on the defensive, opening the space is more important than ever.
Bavaria with a rigid system
If a team uses only one formation, however, you can attacking play are very rigid. The Bayern Munich in the last few weeks are often confronted with these allegations. Your 4-2-3-1, which is interpreted as an offensive defensive system with a few changes, has currently acute problems opening the opponent's four chains.
It is no coincidence that the three goals were scored in Munich the second half from set pieces. The opponent is made it easy to double the opponent's defense, movement, and reshuffles in the offensive system is scarce. Thus, the attacks of the master record will ausrechenbar.
More flexible systems, less rigid game
The trend is therefore away from the rigid game system more flexible way to play. Even the teams that rely more on the classic version, would find the 4-2-3-1. Many teams just lock teams on the benefits of 4-4-2 (second face-off station in the head with fast counterattacks).
Teams with solid defensive saddle, as the first FC Nuremberg come from a 4-1-4-1 and close the midfield with three central midfielders.
For years, presented as a tactical analysis of a "team plays the usual XY 4-2-3-1".
But the recent examples show that one must look closely in the future, if you want to decode the playing style of a team.