Guiding unfancied Villarreal to the Champions League semi-finals ought to have been a career highlight for Unai Emery, the manager who has taken a team from a town with a smaller population than Clacton-on-Sea to the pinnacle of European football.

Yet a common theme of the Yellow Submarine's run to the last four of the continent's premier competition has been the criticism directed at the 50-year-old former Arsenal boss.

After knocking out Juventus in the last 16, the Italian side's manager Max Allegri was unhappy with what he perceived to be Villarreal's defensive approach, ignoring the fact the Spaniards had the majority of possession in the first leg and, with the tie delicately poised at 0-0 at half-time in the second leg, that it was Emery's team who went in search of victory. They scored three times in 45 minutes to progress.

In the quarter-finals, Villarreal stunned Bayern Munich, whose manager Julian Nagelsmann also criticised Emery's tactics. Nagelsmann conveniently forgot that in the first leg, the La Liga side had missed a number of chances that could have earned them a more convincing lead.

Then came the semi-final against Liverpool and the fiercest condemnation yet following a 2-0 defeat at Anfield, a scoreline they will attempt to overturn in Tuesday's second leg.

One UK radio pundit described Villarreal as "a disgrace" to the Champions League, calling them "pathetic".

That view was quite rightly rejected by just about everyone from both sides, with the reality being that Villarreal have a budget of just under £100m, while Liverpool's is around six times that amount.

All that criticism begs the question: Does Emery get the respect he deserves?

Still doubted in England?

Three consecutive Europa League triumphs with Sevilla, a clean sweep of France's domestic competitions in 2017-18 at Paris St-Germain and a further Europa League success last year - Villarreal beat Manchester United in the final to win a first major trophy in their near 100-year existence - ought to have confirmed Emery's place as one of Europe's elite managers.

Yet in England, his ultimately unsuccessful spell at Arsenal appears to have clouded the way he is perceived.

In 2018-19, his Arsenal side had two shots at qualifying for the Champions League, but failed with both. They were pipped to fourth spot in the Premier League on the final day of the season by rivals Tottenham, then lost to Chelsea in the Europa League final. Those disappointments would ultimately define his Arsenal tenure and he was sacked within six months, but the margins were small and actually, in many ways, his first year in England had been a really positive one.

His inability to speak perfect English was apparently one of the main reasons for his failings although, paradoxically, he enjoyed greater success in his first season at the club than in the second, when presumably his English would have improved. He was dismissed with the Gunners on a seven-game winless run and, of course, the reality is that had results been better Emery's English, or lack of it, would not even have been mentioned.

The truth is there were a number of reasons things did not work out at Arsenal, not least the fact that young players such as Bukayo Saka and Emile Smith Rowe, who have become focal points in the team, were too inexperienced back then and required time to develop.

The club were also in a transition period after more than 20 years of doing things in a particular way under the leadership of Arsene Wenger. They tried to change with a group of people put together who didn't know each other and lacked synergy.

That, the lack of patience and the constant thorn in his side that was Mesut Ozil was always going to make the manager's life inordinately difficult. And, as Mikel Arteta would also find out when he arrived, many of the players were simply not as good as they or many at the club thought they were. Expectations were greater than the quality of the squad.

Emery himself would admit that when things started to go wrong, he could not improve the dynamic. But he left the club a couple of steps ahead of where they were when he arrived.

Emery is viewed very differently in Spain, where he is admired for his meticulous approach and tactical awareness.

It is typical of him that he spent four days before the game at Anfield last week ensconced in the Villarreal Sports City complex making micro studies of the entire Liverpool side. In the process, he watched 15 of the Reds' matches in their entirety.

It brings to mind the quote of Joaquin, who played under Emery at Valencia. He said of the coach: "Emery put on so many videos I ran out of popcorn! He's obsessed with football - it's practically an illness. He's one of the best managers I've had. I worked with him for three years. I couldn't handle a fourth!"

Emery's game plans inevitably entail looking at and ticking off a check list of everything you want to achieve from a match.

He knew above everything else that to try to go toe-to-toe with Liverpool at Anfield would have ended in embarrassment, although it is certainly true he wanted more from his side.

He doesn't need anyone to tell him that the team needed to attack better, retain the ball for longer periods, avoid making mistakes in their build-up play, show courage with the ball, attack the spaces when available and be mentally strong when in possession.

The only instruction he successfully managed on Wednesday was to prevent Liverpool opening them up with set-pieces. Everywhere else, his side was found lacking. None of those boxes were ticked at Anfield and that, coupled with Liverpool's unbelievable ability to maintain pressure high up the pitch and press with intensity for the whole game, was why Villarreal became ultra defensive. It was not because they wanted to play this way, but simply that they had no other option. They were not allowed to do or be anything else.

Liverpool manager Jurgen Klopp himself was never going to make the mistake made by Allegri and Nagelsmann in underestimating Villarreal and he will not need reminding that, despite their superiority, they only scored twice in that game. With Gerard Moreno back in action for the home side, we could well see a different Villarreal on Tuesday.

What does the future hold?

As unlikely as a dramatic Champions League semi-final comeback might be for Villarreal, victories in the past year over Juve, Bayern, Manchester United and Arsenal should serve as warning enough for Liverpool.

And if Emery's side do produce something spectacular on Tuesday, it would surely be Emery's finest moment. It would underline why PSG and Arsenal appointed him - and why other leading European clubs might consider him a viable option.

But any talk of a move to one of the major players in La Liga - or perhaps taking over as Spain coach when Luis Enrique's contract runs out after the World Cup - is currently way off the mark.

He feels at home at Villarreal, not least because he is also enjoying the rekindling of a relationship with his son Lander, now 18. Emery is closer than ever now to his son, after missing out on his formative years because of divorce and travelling around Europe and other parts of Spain.

In club president Fernando Roig, Emery has discovered a like-minded person with a very similar ethos, someone who made his future and his fortune by creating a culture based on hard work, process and progress.

Along with club vice-president Jose Manuel Llaneza, they have created the perfect environment for the manager to put his plan into action, one which is not about him as a personality but fundamentally about making players better and the team more competitive.

Beating Manchester United in last season's Europa League final proved to the club's fans that they were not there to make up the numbers, but a club that could compete - and win - at the very top level.

The progress has satisfied Emery, which means the Premier League is not in his thoughts at the moment. He believes he still has much to accomplish at Villarreal. He was Newcastle's first choice at one stage in their search for a new manager earlier this season, but he did not want to leave behind all that he is building now.

The English top-flight does remain unfinished business for him, though, and he wants to test himself in Serie A too.

Barcelona and Real Madrid will probably never be on his horizon, nor he on theirs, since his style and personality would not be seen as a match for either club.

So for the time being, Emery is happy where he is.

Right now, that is almost certainly in self-imposed exile at the club's Sports City complex, trying to discover a way of causing a major shock when Liverpool visit on Tuesday.