Though Dele Alli's horror tackle and Tottenham's struggle at Wembley as a whole will no doubt be discussed at length over the next few days, one of the most alarming aspects of life on Hotspur Way has undoubtedly been the form of Eric Dier.

Last season, the 23-year-old was largely indicative of all things good about Mauricio Pochettino's vibrant young side in north London, as well one of few England players to emerge from the Euro 2016 debacle with his reputation intact. Athletic, strong, intelligent and tactically flexible, the defender-turned-holding-midfielder looked like a force of nature at times.

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Dier was always springing surprises. Whether it be his stoic performances in shielding the backline for both club and country or showcasing his ever-improving passing range, the former Sporting Lisbon man had layers to his game not wholly apparent when he first arrived from the Portuguese capital.

In fact, watching him lining up a free-kick against Russia on the 11th June in Marseille may have confused at first, but he dispatched a stunning free kick with a surprising expertise from a dead ball situation.

Still, as much as he represented this new chapter for Spurs last term, Dier is quickly becoming symbolic of what's going wrong for Pochettino right now. That's not to say the Argentine is in a crisis at White Hart Lane, though the England international's form should be a major concern.

The intensity and fluidity that have proved so important in Tottenham's setup is becoming increasingly harder to hit on a regular basis, with Dier in particular struggling to get going often enough. Cushioned by a bumper new deal he penned as a result of last season's form, he's looking like a man entirely bereft of confidence.

The arrival of Victor Wanyama over the course of the summer has obviously impacted him, with Pochettino dropping him back into central defence either to cover injuries, or when he wishes to deploy a 3-5-2 system. Lapses in concentration have been a major part of his performances this season, with the 23-year-old at fault for goals against Liverpool and Gent over the past few weeks.

And therein lies the root of Tottenham's problems: it's all in the mind.

Pochettino has previously publicly questioned his side's desire to truly challenge the top order of the Premier League, believing they struggle to 'cope with pressure' at times during the campaign. Dier's shaky performances in central defence lend themselves to continuing that miserable theme, despite the fact he impressed so much last season.

It's been refreshing to see Tottenham change their stance over the past few years. For a football club who'd so often change managers season by season, the idea of having one man try to build something long-term would have been a welcome one in north London. Still, it very rarely seems as if the root of the problems are sufficiently addressed at the club.

"It is difficult to fight for the Premier League if you show that lack of desire to play for a win."

Dier needs to be dropped, it's as simple as that. Not for just one game, he seriously needs to find the sort of spirit and determination that made him such a force last season, or risk being labelled a one-season wonder.

It's easy to blame Tottenham's mentality, though what is being done to improve on it? Entirely bereft of confidence or even the ability to concentrate, Pochettino sorting Dier out would be a major indication he can start to work on their mental strength.

Does he get a free ride because of his performances last season? Perhaps. Does he get a free ride because he's young, English and very rarely hitting headlines for the wrong reasons? Absolutely.

If Spurs are ever going to stray from the mentality Pochettino has talked about so openly, it's situations like this that need to be dealt with in a decisive matter, or they risk holding on to the fragility tag so readily associated with them in times of pressure.

For Dier too, he's at a crucial stage in his development as a footballer.

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