As they prepare to face Arsenal, here's how manager Pep Guardiola has made the European champions even stronger
Under Louis van Gaal, the godfather of Bayern's possession game and Jupp Heynckes, his more pragmatic and tactically refined successor, it was easy to predict Bayern's lineups. They always formed-up in a 4-2-3-1, changes were always injury-enforced, and both coaches would simply try to find replacements that would most closely resemble the properties of the missing regulars. Under Guardiola, that kind of certainty has largely gone out of the window. Only the back-four are settled. Philipp Lahm's transformation into a holding midfielder seems to have become permanent but it's still possible that the captain will find himself back in the right-back role later this season. Javier Martínez, Bastian Schweinsteiger, Thiago Alcântara and Toni Kroos are all vying for places in midfield and have been used in different roles. Further upfield, the injured Franck Ribéry and Arjen Robben have remained untouchable, but the two central attacking slots are being changed every game, in accordance with the strengths and weaknesses of the opposition.
Guardiola's football philosophy is based on dominating possession, creating a constant numerical advantage in midfield and aggressive pressing. The 43-year-old has not been afraid to deviate from his principles when necessary. In the 3-0 win at Borussia Dortmund in November he ordered his centre-backs to play long balls out of defence to escape Borussia's high-pressing. Martínez, the team's ball-winner, was stationed high up behind the striker Mario Mandzukic to win the headers and to put pressure on the opposition's midfield. This destructive ploy worked well and both Dortmund's and Bayern's passing rhythm was thoroughly disrupted. Guardiola reverted to a "false nine" system midway through the second half, to exploit the spaces that were beginning to open up.
Smaller and more subtle tweaks are constantly being employed before and during matches. Xavier Sala-i-Martín, a professor of economics and a former Barcelona treasurer, has compared Guardiola's "continuous innovation" to the highly-flexible production process of Spanish retailer Zara. Zara's collections are more expensive to produce than those of rival chains but change much more frequently, in line with trends or micro-trends. Both Zara's and Bayern's output is still defined by a grand framework but within that, flexibility is just as important: employing the appropriate micro-tactics for any given situation takes precedent over dogma.
Last season, Heynckes had one move that he would repeat again and again. As soon as Bayern were in front in a big match, Luiz Gustavo would come on as a second holding midfielder in place of the central midfielder, with Schweinsteiger moving up into the vacated No10 position. There was no need to come up with any different ideas because this one worked beautifully, all the way to the Champions League win at Wembley.
Guardiola, like Van Gaal before him, is much more radical and pro-active on the touchline. He frequently changes players, positions and formations in the middle of a match if he feels that the opposition has found a way to deal with the initial plan. Lahm ended up playing four different positions in the 4-1 win against Mainz. Guardiola's interventionism often impacts negatively on the flow of Bayern's football – too many changes can make them disjointed – but they tend to get the job done.
Providing Guardiola with a midfielder who could play as a withdrawn striker through the middle cost Bayern €37m (£30.3m) and a lot of goodwill from neutrals, who felt the move was both vindictive towards Dortmund as well as a bit of overkill. With time, it has become apparent why the Catalan wanted Mario Götze (or a Götze-type player): playing the 21-year-old instead of an orthodox striker has made it much easier for the treble winners to break down negative opponents who defend in a "medium-to-low block" (as André Villas-Boas would have it) near their own penalty box. Götze can dribble past players or go wide to overload areas occupied by the wingers, and he helps Bayern control the tempo and the ball by falling deep, as well.
In addition, Guardiola has fielded Thomas Müller, initially a striker who was converted into a free-roaming or wide midfielder, in the Götze role, most successfully in the 3-1 win at Manchester City. Müller, hard to define at the best of times, has interpreted the role slightly more like a forward, in terms of positioning; as a slightly less false nine, if you will. The Peru veteran Claudio Pizarro would also fit that bill, owing to this propensity to go deep and join up with the buildup play. As a result, there are three different ways in which the sharp end of Bayern's attack can take shape.
Bayern are a little lop-sided in the wide defensive positions. David Alaba, who plays in midfield for Austria, is fast, technically proficient and phenomenal. Rafinha, his Brazilian counterpart, on the other hand, is solid rather than spectacular and often looks like the team's weak link. Guardiola came up with an idea that would play to their respective strengths and their weaknesses: he ordered them up the pitch but infield, closer to the centre-circle than to the touchline. In possession, Bayern had even more options in the centre of the pitch. Opposition wingers were unsure whether to move inside too or to protect the space in front of their full-backs. More possession – and specifically more central possession – has brought out the best in Alaba but also reduced the risk of Rafinha being isolated on the right. In recent games, the full-backs were playing in a more orthodox fashion again but it proved a very useful ploy in the first half of the season.