Guardian.co.uk's David Hytner reported:
De Bruyne accepted that his opportunities at Chelsea would have been limited, in light of the club's £65m summer spend on attacking midfield talent; they have signed Eden and Thorgan Hazard, Oscar and Marko Marin, and they do not intend to stop there. The German club have no option to make the deal permanent.
This article will assess the Blue's decision to loan De Bruyne out to Werder.
Kevin De Bruyne would have been a perfect super sub for Chelsea because of his ambidexterity, his playmaking ability, his shooting and his expansive passing range.
Loaning him out to Werder Bremen is bizarre, because the Bundesliga is totally different to the Premier League.
Surely if Chelsea wanted to nurture the Belgian, they would've loaned him out to a Premier League club, like they did with Daniel Sturridge, who thrived for Bolton Wanderers.
Thomas Schaaf relied heavily on three players: Claudio Pizarro, Philipp Bargfrede and Sokratis Papastathopoulos.
In the Greek's case, he was the best right-back and centre-back in the team, which didn't say a lot about the club's depth at full-back.
What about Marko Marin? Injuries aside, Schaaf's resolute belief that Marin would be an elite No. 10 was a main factor in the 23-year-old's dramatic loss of form.
Kevin De Bruyne is going to a Werder team that are in a rebuilding phase.
In the past two seasons, they've let go of: Pizarro, Marin, Tim Wiese, Naldo, Per Mertesacker, Torsten Frings, Petri Pasanen and Markus Rosenberg.
Kevin De Bruyne isn't lightning quick and doesn't possess the trickery to consistently get past full-backs.
Last season, he struggled in the UEFA Champions League to get in behind Gonzalo Castro, José Bosingwa and Miguel—all three are medicore at best.
De Bruyne doesn't want to play on the left, and he has enormous upside as a No. 10. In a five-game stretch as an attacking midfielder, he scored once and provided six assists.
Where's Philipp Bargfrede? Unfortunately he injured the medial ligament in his left knee, which is terrible news because he is Werder Bremen's answer to Owen Hargreaves.
So don't be surprised if Bargfrede picked up more injuries because he was rushed back to soon.
Eljero Elia's career has been in limbo but he does have pedigree.
Theodor Gebre Selassie should provide a spark down the right as he did for the Czech Republic during Euro 2012.
Marko Arnautović is a poor man's Mario Balotelli and the Austrian may never fulfill his potential.
Nils Petersen, a forward on loan from Bayern Munich, is an interesting prospect. As long as he doesn't take 8.2 shots per goal like Markus Rosenberg, Petersen should be fine.
Klaus Allofs has recruited quite well, but it's up to Thomas Schaaf to change his 4-3-1-2 formation to a 4-2-3-1.
Kevin De Bruyne must have felt awkward when Chelsea signed Eden Hazard.
That feeling turned into emptiness when Oscar was signed.
Unless De Bruyne becomes one of the Bundesliga's best players, he'll return to the Blues as a squad player.