Bayern Munich's lack of progress under Julian Nagelsmann highlighted in Villarreal defeat

Julian Nagelsmann had big - nay, colossal - boots to fill when he arrived at Bayern Munich at the beginning of the season.

Hansi Flick, who earned seven titles in the 18 months he spent at the helm of the German giants, was the man he succeeded. To be fair, serious improvements were never going to materialise - simply because you can't improve upon perfection.

But, since Nagelsmann's arrival at the club, the only onfield steps Die Rekordmeister have taken are backwards. And that was made clear by a sensational Champions League performance from Villarreal on Wednesday night.

Unai Emery's Yellow Submarine sank Bayern with a collective display that had everything; from gutsy, regimented and unselfish defensive diligence, to dynamic, enthralling and pacey breakaway moves, Villarreal were too much for the team tipped for continental glory this term.

Flick's Bayern consisted of outright ruthlessness throughout his reign; Nagelsmann's Bayern have on several occasions fallen short of those standards since mid-December this campaign.

The departures of David Alaba and Jerome Boateng and the unphased propulsion to first-team regularity of Dayot Upamecano seem to have been catalysts for defensive errors.

The Frenchman has metamorphosised from a precision-focused, bulldozing rock at RB Leipzig into a hesitant, error-prone, shaky mess at the heart of the Bayern back line. Indeed, the 23-year-old was to blame when Dani Parejo was afforded the freedom of eastern Spain as his shot was diverted into Manuel Neuer's net by a grateful Arnaut Danjuma.

It must be noted, however, that Benjamin Pavard (who was caught dozing and failed to spot the Dutchman at the back post) and Jamal Musiala (who failed to track back and follow Gerard Moreno's run into the box) were also guilty parties in that fatal sequence of play.

That decisive goal in Villarreal's 1-0 victory over Bayern on Wednesday was symptomatic of what Die Roten have become as this campaign has trundled on; they've lost their invariable alertness and killer instinct and they've lost their reputation as untameable beasts.

Usually, their newfound penchant for defensive disorder is bailed out by their divinity upfield.

But, coming up against a perfectly drilled, insatiably spirited and collectively compact defensive shape like Villarreal on Wednesday night, they had no answer.

The typical electricity of Kingsley Coman had no end product, the elegance and wiry quality of Serge Gnabry was stifled by the workhorses in yellow, the usually elusive Thomas Muller was marshalled to perfection in a crowded midfield, and Robert Lewandowski? Well, he might as well have stayed in Munich.

While Flick's monstrous machine gave their opposition no option but to succumb to their glisteningly merciless magic, Nagelsmann's men too often find no answer to sticky situations - this has been the case against Bochum, Salzburg, Bayer Leverkusen, Hoffenheim and Villarreal in the space of their previous ten matches across all competitions.

The young, pioneering German will inevitably secure the club's 10th consecutive Meisterschale come May - their nine-point cushion at the Bundesliga summit with six games remaining seems unassailable now - but their inability to rise above top opposition and distinguish themselves (as they did under Flick) has been truly highlighted by an excellent Villarreal performance on a magical night.

Until individual errors and 2D attacking disappear from these clutch moments, Bayern are a long way off Champions League success under Nagelsmann.