Chelsea boss Jose Mourinho has described his ideal January window as one of players neither leaving nor arriving at Stamford Bridge, but if there's one regular first-teamer who might find himself thrown on the transfer scrapheap this month, it's undoubtedly German international Andre Schurrle.

A withering impersonation of his productive self from last season and at the World Cup in Brazil, it's been a half-campaign to forget for the former Bayer Leverkusen star. Managing just 419 minutes in the Premier League and subbed off at half-time in his last two appearances, is it time Chelsea sought an upgrade on the misfiring winger-forward?

Of course, Schurrle's the type of player whose impact is felt over the course of an entire season. Last term for example, scoring just three in his first 27 appearances across all competitions for Chelsea, it wasn't until a 20 minute hat trick against Fulham in March that the German international  truly looked worth his £18million transfer fee. He went on to finish his inaugural campaign at Stamford Bridge with nine goals, including eight in the Premier League. Only Oscar, Samuel Eto'o, Fernando Torres and Eden Hazard contributed more.

A versatile forward blessed with penetrative pace and a deadly, albeit rather inconsistent, eye for goal, the 24 year-old remains immensely valuable tactically. Not only does he give Mourinho the option of changing formations and systems mid-game without substitution, but he furthermore poses a regular goal threat - or at least, a constant testing of the opposition goalkeeper - from any position in the final third. He's even been utilised as an out-and-out striker by the Chelsea gaffer on occasion, particularly at Old Trafford last season, and potential injuries could well see him called upon in that capacity once again. He fills small yet significant gaps in Chelsea's squad depth, and in comparison to Willian, Cesc Fabregas and Oscar, is the Blues' only attacking midfielder that offers natural width.

Yet, the Premier League's uniquely chaotic winter schedule should be the opportune occasion for players of such positional flexibility to truly come to the fore, filling in wherever necessary for more exhausted personnel. Over the course of the Christmas period however, it's been a reverse of fortunes for Schurrle; he was hauled off at half-time against Southampton and again in the FA Cup against Watford, whilst failing to even make the bench for Chelsea's shock 5-3 defeat to Tottenham.

It's a regression of form that can be traced back to Schurrle's exploits at the World Cup, perhaps giving an insight into his current psychology. The German forward netted a semi-final brace against Brazil and provided the assist for Mario Gotze's tournament-winning strike against Argentina, but has since portrayed a player desperately struggling for motivation, less prepared to contribute defensively and lacking drive and confidence going forward. As Arsene Wenger has recently argued in regards to Per Metesacker, having already reached the pinnacle of the beautiful game at just 24 years of age, maybe Schurrle's simply suffering from an inevitable World Cup hangover.

His individual style of play isn't particularly favourable either; Schurrle's speculative shoot-on-sight policy serves equally as a blessing and curse, making him either Chelsea's match-winner or the scapegoat for their profligacy in front of goal, especially combined with his ever-turbulent work-rate. The German international's been without his shooting boots so far this season, but as soon as some of those tentative efforts begin trickling into the corners of the net once again, frustrations towards Schurrle will naturally decline.

At the moment however, it feels more like a case of if than when. Historically, Mourinho has never been a manager that waits around for form and Chelsea are hardly in a position to depend on variables - their six point lead on Manchester City from earlier in the season has now whittled down to the advantage of alphabetical order alone.

Whether Chelsea can find an upgrade on Schurrle in the space of a single calendar month, however, remains to be seen. They were linked with Borussia Dortmund star Marco Reus earlier in the season, but recent speculation suggests Real Madrid's Bernabeu will be his likeliest destination, if a move is to take place this January at all. Then there's Fiorentina's £30million-rated forward Juan Cuadrado, a more elegant and potent incarnation of Willian, Barcelona's Pedro, who allegedly fancies a change of scene, or Schalke prodigy Julian Draxler, but bringing any into a title challenge mid-season and expecting them to hit the ground running is a rather risky strategy.

For that reason alone, Schurrle might just see out the summer at Stamford Bridge, but at this moment in time it's almost impossible to envisage his Chelsea career spanning much further.