A creeping apathy spreading across Premier League grounds, long diagnosed and discussed by fans, seems to have reached the dugout and the boardroom. In recent weeks, a trio of London-based managers questioned their own supporters.
First, André Villas-Boas queried the atmosphere at White Hart Lane after a nervy, scrappy 1-0 victory over Hull City. "We didn't have the support we should have done. There was so much anxiety from the stands, the players had to do it alone," he said.
Last Saturday, it was José Mourinho's turn to wonder whether the "profile" of the Stamford Bridge crowd had contributed to a lethargy that matched his team's performance in scrambling a draw with West Bromwich Albion. "We know Stamford Bridge is not a very hot atmosphere, not a very strong atmosphere normally, and we accept that," he said.
Last month, at Arsenal's agm, Arsène Wenger told fans: "We will need your support and we had some moments where at the Emirates we did not always feel that, but I can understand that, because it is up to us to give you the belief and it is not for you to give us the belief."
The diagnosis is by no means universal. For big games and on heady European nights, the atmosphere at most grounds can still make the spine tingle. At others, such as Stoke City's Britannia Stadium, it crackles no matter the opposition. But elsewhere there is a definite feeling that something is being gradually lost from the matchday experience.
That could, ultimately, have a knock on effect on the soaring overseas television revenue that contributed to a £5.5bn windfall for clubs for the three seasons starting with 2012-13. One of the key factors that helps make the Premier League the most saleable commodity in world football is its noise, pageantry and atmosphere.
Whenever a new overseas owner buys a Premier League club it has become obligatory to say that the atmosphere is one of the things that has drawn them in.
On the eve of the new season, the Premier League chief executive, Richard Scudamore, said fans were an integral part of the "show" being sold around the world for an ever higher price tag. "We can't be clearer. Unless the show is a good show, with the best talent and played in decent stadia with full crowds, then it isn't a show you can sell."
There is a danger discussion of the issue becomes an exercise in rose-tinted nostalgia, however. That those waxing lyrical about the passion of earlier decades have blocked out the more unsavoury, unsanitary flip side of watching football in the 70s and 80s.
But there is a groundswell of opinion, now recognised by many clubs and managers, that the pendulum has swung too far the other way and that one of the factors that has defined English football – its vocal, passionate crowds – is at risk of ebbing away if no action is taken.
A cocktail of factors have been at play for some time. The switch to all-seater stadiums, in many cases largely filled with season ticket holders, has had a clear effect in preventing more vocal fans from massing together as they did in the age of terracing.
The demographics of crowds has undoubtedly shifted. Whether or not they are getting steadily older is much disputed. The average age of an adult fan in the Premier League is 41, according to its surveys. But these also point out that 13% of season-ticket holders are children and almost a fifth of those who attended games in 2012-13 were aged between 18 and 24.
Whatever the stats say, one only has to look at a Premier League game to appreciate a shift. Just as the 17-24 range has been identified as the crucial age when homegrown talent is withering on the vine on the pitch, so there seems to be a growing vacuum among young adults in the stands. Children will sit in the family section, or are enticed by one of the growing number of offers introduced by Premier League clubs in recent years. But once young supporters no longer qualify for a concessionary ticket, watching in a pub among their friends seems to have replaced going to the match as a rite of passage.
As the age profile has risen, along with the price of admission, so has the mindset. "We'll never go back to where we were in the 70s and 80s. You could pay on the gate, it was much cheaper and you could congregate together," says Tim Rolls, chair of the Chelsea Supporters Trust.
"The atmosphere is still good at away matches. But at home, it's partly the demographic changes. Also, there are more tourists, it's an experience and they're there to capture it on their iPad rather than interact. Also, people have got older," he adds. "The people I go with I went with in the late 70s. Around me, there's so many people over 45. With the best will in the world, you're not going to get as much noise out of them."
Tim Payton, the Arsenal Supporters' Trust spokesman, said that some problems were peculiar to the Emirates, such as the firebreak created by the ring of 6,000 corporate seats around the stadium, which has turbocharged the club's matchday income but harmed the atmosphere.
"There is no doubt the pricing has led to a certain type of gentrification. In some ways it's probably better in that it's brought in more families, more children. But maybe you've not got a community of people that want to sing," he said. "It's the pricing, it's the new generation of fans, it's the seating. It's a bit of all of that."
At Tottenham, the 1882 collective originally started out as an internet flashmob that would turn up at youth matches and try to recapture the atmosphere of old. More recently, they have tried to do a similar thing for Europa League ties and others where tickets are easier to come by, and the club has begun to help out by moving like-minded season ticket holders into the same block.
That has sparked a debate on fan message boards. Some accuse the 1882 crowd of being too "cliquey" and suggesting the organised nature of the singing is "embarrassing", while others laud it for attempting to recapture a backdrop historically considered one of the best in London.
Most agree on the problem but solutions are harder to come by. Large-scale price cuts are unlikely, to say the least.
Those who advocate following the Bundesliga model of safe standing argue it would be a big step in the right direction. Many big clubs are privately softening their attitude but the long shadow of Hillsborough means that political will for change remains unlikely, while unreserved seating would face objections from the police.
Manchester United trialled a singing section at their Champions League tie with Real Sociedad and 6,000 fans applied to be seated in the 1,500-capacity section. A coalition of fanzines and fan groups distributed letters on each seat urging fans to get behind their team and the experiment was judged a success. Arsenal have introduced a "teenagers for a tenner" section, which offers up to 1,000 tickets for £10 at home matches.
The recent furore over high prices for away fans, which culminated in a march on the Premier League headquarters last summer, also feeds into the debate. Away fans are crucial to creating a vibrant mood and most clubs report that their away contingent – younger, committed and grouped together – often make more noise than at home.
The Football Supporters' Federation (FSF) has had an encouraging response to its Twenty's Plenty campaign, with the Premier League putting aside £12m over three seasons to encourage away support. Some are using it to subsidise travel for their own supporters, others to cut prices for visiting fans.
Kevin Miles, chief executive of the FSF, said that Premier League clubs had started to engage on away ticket pricing because they realised the impact it could have on the overall matchday experience and on television income if numbers fell. "The introduction of cheaper pricing and standing areas would go a long way to bringing back some of the atmosphere," he said.
Clearly there is no silver bullet to address the subdued mood on matchdays but clubs and fans' groups alike at least recognise there is a mutual benefit in looking for solutions to a long-gestating problem that has left Nirvana as the unlikely soundtrack to many matchdays. "There's a definitely now a big element of 'here we are now, entertain us' with many fans," Rolls said.