This time about a year ago, before Mohamed Salah at Liverpool began to push his way to the front of the queue for the nation’s attention, a debate was taking place over whether the increasingly reliable Harry Kane was good enough to be regarded as genuinely world class. Now the same thing is happening in reverse to Alexis Sánchez. By the time the Chilean left Barcelona for Arsenal his credentials as one of the world’s elite were impeccable. Last month a journalist in Santiago made contact asking for information on why Sánchez was failing so badly at Manchester United.

Genuinely world class. The first word ought to be superfluous, though in football discussions it never is. No one quite knows the parameters here. Some would argue you have to be good enough to hold down a place in a notional World XI, to take part in a pan-galactic match against Planet Zog. Others think that might be a bit harsh, and suggest any pan-galactic contest would surely be organised along World Cup lines and would therefore require a squad of 23 players, perhaps even a couple more. So you could envisage the criterion as being enough players to form a trial match between the best two sides in the world.

Next Generation 2018: 60 of the best young talents in world football Read more

Or you could dispense with the extraterrestrial stuff altogether and conclude that roughly speaking, most seasons, we already know the best two sides in the world. A simple, working definition of world class might be reduced to this: anyone good enough to attract serious interest from Barcelona or Real Madrid.

With apologies to Bayern Munich, Juventus, Manchester City and anyone else who might feel slighted, that is the definition we will be adopting for the rest of this article. Kane would have made the cut at various times last season – he was certainly on the Spanish giants’ radar and his goalscoring feats were being favourably compared with those of Lionel Messi and Cristiano Ronaldo – though he did not quite manage enough to boost his standing at the World Cup despite winning the Golden Boot, and he seems to have been suffering a hangover ever since. At his very best Kane might be world class, though since he has been far from his best this season the point is moot.

What is not is that other Premier League luminaries are also struggling to stay at the highest standard. Sánchez and Mesut Özil both must have been world class once; they not only played for Barcelona and Real Madrid respectively, they both won titles in Spain, not to mention the latter’s World Cup win with Germany. Neither is managing to convince at the moment, in fact some of the more strident supporters of Manchester United and Arsenal have been questioning their wages and value to the team.

The Fiver: sign up and get our daily football email.

Class is supposed to be permanent, or at least that is how the saying goes, yet even though the pair are still in their late 20s they would not now be near the top of a list of the world’s greatest players. Theoretically yes, both remain remarkable footballers, though some element of consistency is implied in the world-class compliment. It is not enough just to have the ability, it is also necessary to show it again and again, in different circumstances, sometimes against the odds. Think Sergio Ramos, Luka Modric, Luis Suárez or Andrés Iniesta. Or, at a slightly less elevated level, Gianluigi Buffon, Giorgio Chiellini, Philipp Lahm or Arjen Robben. To be regarded as world class it helps to play the long game, to be around for ages. While one or two seasons of outstanding achievement will certainly claim attention, the stricter judges will demand follow-up.

So looking around the Premier League’s elite clubs, who at the moment is demonstrably world class? Perhaps not Kane – until the striker gets back to his best, maybe Christian Eriksen is the most eye-catching player at Spurs and he is out injured. Petr Cech is still capable of impressing but the 36-year-old goalkeeper’s brightest days are behind him.

Facebook Twitter Pinterest Mo Salah was different class last season but can he do it all over again for Liverpool? Photograph: Marc Atkins/Getty Images

Chelsea have the one player who meets all the tests in Eden Hazard, both in form and in demand. Right at this moment, with Kevin De Bruyne injured, Salah not hitting the heights of last season and N’Golo Kanté deployed in a different role to the one that made him famous, Hazard is unquestionably the Premier League’s outstanding player. The Belgian might not have won a World Cup but he is doing far more for his club at the minute than Paul Pogba is doing at Manchester United. Until Pogba sorts out his apparent difficulty with José Mourinho the most reliable aura of greatness at Old Trafford still surrounds David de Gea.

Still in Manchester, De Bruyne’s injury robs City of their most conspicuously creative performer, with due respect to the evergreen David Silva, though few would argue that Sergio Agüero fits most people’s description of an ideal centre forward. Even Pep Guardiola seems to have changed his mind over the last couple of seasons, with Gabriel Jesus not quite ready to step in just yet, although critics might point out that Agüero has rarely been regarded as first-choice striker for his native Argentina in recent years, never mind the world. At Liverpool, Salah was clearly different class last season but the ultimate accolade depends on whether he can do it all over again, and while there is still time to weigh in with another stack of improbable goals the early signs are not encouraging.

The list of definites playing in this country at present, then, can be counted on the fingers of a mitten. There is Hazard, with Agüero quite close, and Salah and De Bruyne waiting in reserve. Even if you throw in names such as De Gea, Kane and Kanté it still does not amount to a lot, especially as only one of them is English. Yet barring Spain, which acts as a magnet for top talent from around the globe, the situation is not too dissimilar to that anywhere else.

The Premier League’s status as the richest in the world means it will probably continue to attract its share of overpriced flops and Spanish hand-me-downs, though English football cannot be doing too much wrong if it produces players such as Trent Alexander-Arnold, Joe Gomez, Ryan Sessegnon, Marcus Rashford and Kieran Trippier, and showcase talent of the order of Roberto Firmino, Rúben Neves and Wilfried Zaha. Somewhere in there might be the marquee names of the future, not forgetting the bold path to national attention trailblazed by Jadon Sancho in Germany. The future looks promising, which is just as well, since many of the present crop of expensive imports are fading from view.