While the Bundesliga enjoys a much-needed spell of variety in the top half of the table, some of the league's so-called 'big names' have endured rather than enjoyed their domestic campaigns this season.

Bad luck has certainly played its part, but 13 games into the season there's no disguising the fact that three clubs in particular have been playing significantly below expectations.

Wolfsburg

It's hard to start anywhere else than with Wolfsburg. The Wolves are off to the worst start in their history, with just 10 points after 13 games and they collapsed woefully, but entirely predictably, this weekend at home against Hertha Berlin. Wolfsburg twice threw away a lead and still haven't won at home this season.

The departure of Dieter Hecking hasn't improved them, and neither has the appointment of Valerien Ismael, who was widely regarded as an uninspiring choice from a shallow pool of applicants. After exciting Euro 2016 campaigns, Julian Draxler's mood makes more headlines than his performances and the much-heralded signing of Mario Gomez hasn't exactly been a roaring success.

For the team who were the last to beat Real Madrid (in a competition they may remember called the Champions League), this seems an inexcusable fall from grace. Poor individual performances, notably from the leading players, along with poor management and a perceived weakness of character, have left Wolfsburg looking dizzy from the success of recent seasons. The only bright spot is that they appear likely to be spared the true embarrassment of relegation because there are two or three worse teams.

Bayer Leverkusen

Leverkusen are another example of a club floundering. Roger Schmidt has been in charge since 2014 and after that length of time, fans may believe they are entitled to expect to see progress. Against Freiburg on Saturday, Leverkusen failed to have a shot on goal in the first half of a league game for the first time in five and a half years. On top of that, this is their worst start to a league season in a decade (17 points from 13 games) and that 1-1 draw at the weekend showed why. One bad half was followed by one good as Leverkusen were once again left empty handed. It's their inconsistent season in microcosm.

You don't have to look far back to uncover further evidence of the inconsistency that haunts them, a superb win and performance against Borussia Dortmund was immediately followed by a disappointing defeat to Werder Bremen.

Granted, they've had their fair share of misfortune this season - they've missed four penalties and Karim Bellarabi and Kevin Volland's injuries have been untimely - but as the halfway stage of the season approaches bad luck starts to look more like bad form. Chicharito's penalty miss against Freiburg was a perfect example of that.

It seems increasingly apparent that Leverkusen were over reliant on the Mexican last season because this season the club's slump in form has been matched with a 453-minute goal drought for the striker. Given this (and the injuries), Roger Schmidt's decision to keep the squad small is baffling. It's beginning to look like Leverkusen might have reached their ceiling with Schmidt.

Borussia Mönchengladbach

The same could be said for Gladbach and Andre Schubert. Winless in their last eight, Gladbach are enduring their longest barren spell in three years. Their away form remains a problem - they've lost their last four on the road - but the manner of defeat on the weekend was certainly troubling. After taking the lead against Dortmund, Gladbach abandoned their attacking play and ended up paying the price for having 38 percent of the ball.

Injuries (notably to Thorgan Hazard and Raffael) have certainly played a role, but Gladbach haven't improved since the departure of Granit Xhaka. The base of the midfield and the defense is lacking. Neither have done enough to sustain a tough European campaign, let alone a domestic campaign aiming to make them a Champions League regular.

While the rest of the league improves, Gladbach look like they're standing still. With four games left before the winter break and Gladbach 11 points off a European spot, can they really afford to just drift through and then make a change? Sporting director Max Eberl must decide and decide soon.