When Rene Meulensteen, Sir Alex Ferguson's former deputy, tweeted United should go for Gundogan, you would have reacted with a perplexed look if you follow German football.
On August 15, Dortmund released a statement saying Gundogan "is expected to be out for two weeks" after sustaining a back injury during Germany's 3-3 draw against Paraguay.
Two weeks later, Dortmund team doctor Markus Braun said Gundogan will need another month to rehab "a stress reaction in the lower spine."
If you read the last sentence in Dortmund's press release, it suggests the severity of Gundogan's back injury was misdiagnosed, via BVB.de: "The extent of the injury was discovered after an examination at the Knappschaft Hospital on Monday following the midfielder's return to Dortmund."
Gundogan sat out the months of September and October and has yet to play in November.
In the lead-up to Germany's friendly against England, Joachim Loew said, via Bundesliga.com: "I'm sure we'll have Ilkay [Gundogan] back again too."
Gundogan, who has resumed training, will be back for Dortmund, but on the bench.
Like Ferguson, Klopp doesn't make sentimental decisions.
What Gundogan did in the past, taking up the mantle after Sahin ditched Klopp for Real Madrid, will not have a bearing on whether he starts this season.
Mohamed Zidan, Klopp's first elite player at Mainz who became a bit-part player for Dortmund, will tell you that.
Lucas Barrios, who had successive seasons of 20-plus goals under Klopp, lost his starting place due to injury and was usurped by Robert Lewandowski, will tell you that.
Who would be the best player to tell Gundogan that waltzing back into Klopp's starting XI is a pipe dream?
Sahin, as seven of his first eight league games in his second spell were off the bench.
Kicker: It's only a formality that Dortmund will buy back Nuri Sahin from Real Madrid for 7M Euros next summer. #BVB— Sandra Goldschmidt (@SanBorussia) October 31, 2013
He only won back his starting position last season, as Sven Bender and Sebastian Kehl were out against Freiburg—Sahin was the Man of the Match that game.
Now Sahin is Klopp's most vital midfielder again, in part because of Gundogan's extended layoff.
Sahin leads the club in tackles per game (3.8) and passes per game (68.7), is third in interceptions per game (2.2) and is the club's second-highest-rated midfielder, according to Bild newspaper's player ratings.
Bender, Sahin's partner in midfield, has won back the ball 66 times in 11 Bundesliga games.
Gundogan isn't just behind those two, but he will also be competing with Kehl for the backup spot.
If you're on the Gundogan-to-United bandwagon, quit imploring your club to sign Gundogan when no one can definitively say if he will return as the Gundogan of old.
Ilkay Gündogan milling around pitchside - shame he's not going to be involved again til the New Year (spine problem) pic.twitter.com/YJ4faNODfs— Andy James (@UEFAcomAndyJ) November 6, 2013
Is there an alternative to him? Yes.
It is Christoph Kramer, a stylish 6'3" central midfielder, whose partnership with former United transfer target Granit Xhaka is a main factor why Monchengladbach are fourth in the Bundesliga.
Kramer and Xhaka combine to complete 89.7 percent of 133.2 passes per game, which is key to Lucien Favre's tactical ploy in playing a No. 9-less formation.
Max Kruse and Raffael drop deep, receive an accurate pass and either score or create (12 goals and eight assists between them).
|LEAGUE ONLY||Gundogan ||Kramer||Xhaka||Ander Herrera||Tom Cleverley||Michael Carrick|
|Passes Per Game||58.6||59.6||73.7||38.9||56.0||77.0|
|Pass Success %||86.2||90.9||88.5||80.9||89.7||86.8|
|Long Pass Success %||76.9||88.9||81.7||60.9||79.1||76.1|
|Tackles Per Game||2.3||2.5||2.4||2.7||2.4||1.9|
|Interceptions Per Game||2.3||2.1||2.2||0.8||1.0||4.0|
 2012-13 statistics used; everyone else is 2013-14.
Before you say, "Cleverley is statistically comparable to Kramer":
You're right and this is why you should never judge a player on statistics alone.
Subjectively speaking, Kramer looks more assertive, is technically better and affects the game more.
Kramer will take the ball into open space—he averages more dribbles per game (1.9) than Antonio Valencia (1.7) and Ashley Young (0.8)—and cause indecision in the minds of opposing players, who know they have to mark Kruse and Raffael.
Kramer is technically brilliant and routinely embarrasses players who tackle without conviction.
He possesses a sleek Maradona turn, he can nutmeg players and he is two-footed.
In comparison, Cleverley is predictable, he doesn't take on players (0.3 DPG) and he is not suited to a 4-4-2 where the central midfielders have to be able to conjure up moments of brilliance.
OK, you might be wondering: "If this Kramer kid is so good, why isn't he a starter at Leverkusen?"
Stefan Reinartz, Gonzalo Castro, Lars Bender, Simon Rolfes and Emre Can are why Kramer has been sent on loan to Monchengladbach.
Yes, he does have a two-year loan deal with Monchengladbach, but United's money will take care of that issue.
According to Leverkusen's official website, Kramer "even attracted interest from foreign clubs including Benfica".
Benfica were right about Nemanja Matic, Ramires and Axel Witsel.
United can be right about Kramer.