Ilkay Gundogan's career until this point has been incredibly volatile. He was a talented playmaking prospect at Nurnberg before joining Dortmund to replace Nuri Sahin. He then spent more than half of his first season on the bench, an apparent failure. But following six months of rapid progress in the spring of 2012, he made his breakthrough to world-class status in 2012-13.
However, at the beginning of the 2013-14 campaign, he suffered another setback, a back injury that has seen him sidelined since mid-August. And now the status of his career is perhaps the most uncertain of any player in the world.
Gundogan has a contract that will expire in 2015 and should he opt not to extend, BVB appear ready to sell him this summer rather than letting him go on a free transfer a la Robert Lewandowski. Speaking to Sky Sports News (h/t Goal.com) in January, CEO Hans-Joachim Watzke opened the door to a possible sale.
Until recently, it seemed highly likely that Gundogan would be sold. Marca reported in November that in their loaning of Nuri Sahin to BVB, Real Madrid had secured an option of first refusal on Gundogan, who at the time was los Blancos' top transfer target.
Real are not the only interested party. Sport-Bild (h/t Inside Spanish Football) claimed in February that Barcelona had met with Gundogan's agent and father, Irfan, on several occasions. And a week later, Paul Hetherington of the Daily Star wrote that Manchester United were confident of signing Gundogan after offering Shinji Kagawa to BVB. And earlier this month, true to form, Bayern Munich joined the race to sign Gundogan, according to Focus editor Michael Klonovsky.
Gundogan himself has been quiet; his father recently reiterated previous statements to Kicker (via Goal.com) that Dortmund are his first point of contact but that the player will not begin negotiations with any club until he returns to fitness and can play once more.
The situation Gundogan faces is delicate and unique. And for Dortmund it is just the same. The longer the midfielder goes without playing, the more likely it is that he will remain at BVB. He needs only to look to his teammate Sahin to understand the danger of joining a competitive, top foreign club while injured.
There are others, namely Vidal and teammate Paul Pogba, as well as Toni Kroos, who are more in-demand at present. It could be that no great club is willing to pay a hefty transfer fee for Gundogan. But if given an offer, he could also try his luck at another club.
Like Gundogan, Dortmund have been mum about their future plans in defensive midfield. The role Sahin and Gundogan have played in Jurgen Klopp's team is perhaps more important than that of any other player, and adaptation to the point of what the trainer calls "automatism," as reported by Soccerway, can take months or more.
When Sahin left the club in 2011, neither Gundogan nor Moritz Leitner managed to step into his role, and BVB struggled throughout the fall campaign as Klopp was forced to play without a regista-type holding midfielder.
To avoid a repeat, Klopp did a clever bit of business in the January transfer window. BVB were silent in the January transfer window until Jakub Blaszczykowski sustained a season-ending knee injury that prompted questions of whether the club would sign a replacement.
Dortmund then sealed a last-minute deal for Partizan Belgrade talent Milos Jojic, a central player who at first may have been seen as extra depth in attacking midfield. But it seems the 21-year-old may actually be a veiled replacement for Gundogan should the Germany international leave.
Jojic has proved not to be a stopgap to replace Blaszczykowski or even to add depth in his position. On the contrary, the Serb has played just 29 minutes in two Bundesliga appearances since joining. But he has been training since the beginning of February; he will not have an extended summer break due to Serbia's absence from the World Cup and will have spent half a season in Dortmund before next season begins.
Should Gundogan leave, Jojic will be far more prepared for the regista role in Klopp's system than Gundogan was at the time of his signing.
Of course, Jojic is still a prospect whose long-term value is unknown. Dortmund have an immediate replacement in Sahin, whose presence has been hugely important during Gundogan's injury. Kicker reported in October that the Ludenscheid native was set to sign a long-term contract with Dortmund when his loan expires in June, and earlier this week Bild reporter Heiko Niedderer reported that BVB were indeed set to exercise their option to release Sahin from his Real Madrid contract for the fixed price of €7 million.
Should Gundogan leave, Dortmund can expect to have Sahin and Jojic as possible backups. But even if he stays, there is room in the team for at least one of the two to serve as a backup.
Gundogan featured as a central playmaker, supported by holding pair Sahin and Sven Bender in the DFB-Superpokal last July, and the tactic worked brilliantly. The trio played Bayern duo Thiago Alcantara and Toni Kroos off the park in a 4-2 victory. Jojic could similarly be used with either Gundogan or Sahin and Bender, as well as on the left wing.
It can be a difficult and lengthy process for a team to replace a key player, and it's never wise to spend heavily on a replacement before his predecessor leaves. But in Dortmund's case, they've played their hand well. They now have two players who can play the regista role and a third, Jojic, who has the potential to be the next player Klopp converts into stardom.
If Jojic fails to adapt before next season begins and Gundogan leaves, BVB can look to other options in the transfer market. If Gundogan extends his stay, both he and Jojic are capable of playing multiple positions, and Klopp will be able to rotate.
It's difficult to say exactly how things will turn out, but Dortmund have positioned themselves well for the future with or without Gundogan.