We're always open to discussing Bayern's great successes in the transfer window from Robert Lewandowski on a free transfer, signing Mario Götze for less than what Manchester United paid for Luke Shaw (LUKE SHAW!), bringing in a Brazilian centerback (Dante) for nearly €40 million less than PSG have paid for theirs (David Luiz), and activating Thiago's release clause with Barcelona.
Marcel Jansen (€14 million)
After signing from Borussia Mönchengladbach for such a large amount and signing for four years, it was assumed that Jansen would find himself as a regular in the side for years to come. Unfortunately for Jansen, he only finished on season with Bayern before being sold to Hamburg for only €8 million. Oof.
Breno (€12.3 million)
Oh, Breno... He came to Germany with such great promise. Bayern won his signature ahead of other big clubs in Europe. A handful of appearances later, he was being locked in prison for arson after he burned his own house to the ground. Breno is still only 24 years old. Hopefully, now that he's back in Brazil, Breno can figure out a way to turn some of his forgotten potential into a professional career.
Lukas Podolski (€10 million)
Podolski's much ballyhooed transfer to Bayern never really amounted to much. In three seasons, Podolski made 71 appearances and only scored 15 goals. Luckily for Bayern, his hometown club FC Köln bought him back for €10m with one year remaining on his FCB deal.
Sebastian Deisler (€9 million)
Hailed as the future of German football, Deisler couldn't kick the injury bug that plagued his knees. The injuries led to depression, and the former Borussia Mönchengladbach and Hertha Berlin man was forced to retire at the age of 27.
Jose Ernesto Sosa (€9 million)
The man brought in to replace Deisler was Estudiantes's Jose Ernesto Sosa. It's another South American failure in the transfer market for FC Bayern. Sosa spent part of his time with Bayern back on loan with Estudiantes before eventually moving on to Napoli. Sosa is currently employed by Metalist Kharkiv.
Danijel Pranjic (€7.7 million)
Seriously. Danijel Pranjic cost Bayern Munich a lot of money. The Croatian would never make an impact at Bayern. He was pegged as a backup in the midfield and in defense under Louis Van Gaal and Jupp Heynckes. Pranjic would walk on a free transfer at the end of his contract.
Jean-Pierre Papin (€2.75 million)
Papin won the Champions League with Milan before making the move to Bayern Munich. Unfortunately, a lot of his two years in Munich was spent on the physio table. He would win the UEFA Cup with Bayern before bolting for Bordeaux.
Julio dos Santos (€2.7 million)
Dos Santos was never able to figure out European football. The Paraguayan failed to acclimate to Bayern and Wolfsburg (on loan) and found himself back in South America shortly thereafter.
Andreas Görlitz (€2.5 million)
Another perennially injured player, Andreas Görlitz was never able to live up to his initial hype thanks to a series of devastating injuries. He missed nearly two seasons worth of games with Bayern due to said injuries. In current news, Görlitz joined the San Jose Earthquakes of Major League Soccer at the start of the 2014 season. After struggling with injuries at the start of the season, Görlitz was playing well in three matches. Unfortunately, disaster struck again, and Görlitz was out for the remainder of the season with a torn ACL.
Tobias Rau (€2.25 million)
Rau looked to be a potential great defender for FC Bayern when he made the transfer from Wolfsburg, but injuries and French fullbacks Willy Sagnol and Bixente Lizarazu really stifled his growth and playing time. Rau would eventually leave Bayern for Arminia Bielefeld. Four injury laden seasons later, Rau would announce his retirement.
In your opinion, who is the biggest transfer flop at FC Bayern?