Last season it was August, the season before that it was March, the season before that it was January and the season before that it was March and April and bit of May. This season it’s now.

Every year Arsenal have a spell in which they undo the good work that has made them look potential title challengers. That was perhaps the most striking aspect of the defeats by Manchester United and Swansea: that this lack of edge, this failure to seize an opportunity, felt so familiar.

In terms of equivalent results (that is, comparing Arsenal’s result, say, at home against Swansea with last season’s result at home against Swansea, and substituting the three promoted clubs for the three relegated sides), Arsenal are actually a point better off than last season.

Weary familiarity

Which is perhaps what makes this quite so infuriating for their fans, the sense of weary familiarity about this trudge to third or fourth, the

Premier League

trophy gleaming always just out of reach.

Yet this season is different. It’s not quite the same old story, partly because of the unprecedented unpredictability of the league and partly because this time Arsenal are failing in a different way.

They may be accruing an utterly average number of points per game: 1.82 after Wednesday’s defeat by Swansea against a mean over the past 10 years of 1.92, but they are scoring far fewer goals.

After 28 games of the season, Arsenal are averaging 1.57 goals per game. Extrapolate that over the whole season and they’d get 60, which would be their lowest tally since 1999. Over the past decade, they’re averaging 1.88 goals per game.

It would be easy to point the finger at Olivier Giroud, enduring his worst goal drought since he arrived at Arsenal, and Theo Walcott, who has all but dematerialised over the past month. But it is also to do with a shift in emphasis.

It has been evident over the past couple of years that Arsenal have modified the highly technical possession-based approach that became synonymous with late-period Arsène Wenger.

They have tried at times to sit deeper and absorb pressure, an approach that brought the win at Manchester City last season and at home to Bayern Munich this, and they have at times pressed hard and high, as they did in beating Manchester United 3-0. So they are more flexible.

The defensive record is better than it was, say, in the three seasons between summer 2009 and summer 2012, and the crushing defeats away by title rivals have been staunched, but they are conceding a goal a game this season. If that remains constant, they will have let in two more than last season, roughly par for the spell between 2005 and 2009 – when they were scoring 68 goals a season.

Goals for and against per game, though, perhaps doesn’t tell the full story: having an attack good enough to beat lesser sides 5-0 is all very well, but if the defence leaks goals against better sides, it is all but irrelevant in the final reckoning.

Arsenal have scored more than three goals in a game just once this season as opposed to an average of 4.5 times per season over the past decade. At the same time, they’re second (behind Tottenham) in terms of points won per game (1.56) against other sides in the top third. Over the past three seasons, they’ve been sixth, fifth and eighth, averaging just 1.06 points per game.

Drop points

And yet it appears that is still not enough. Arsenal may not get hammered by the elite, but they do drop points against mid-ranking sides. They’re 13th-best this season in games against the middle third.

For years, the belief had been that Arsenal’s problems were tactical, that they were being undone by Wenger’s stubbornness. There may still be some truth to that, but increasingly it is coming to seem as though the problem is mental, that Arsenal, somehow, will find a way to fail. Guardian Service