Arsenal's 5-0 victory over Burnley on the Premier League's penultimate weekend was newsworthy for the aftermath rather than the contest itself, with Arsene Wenger waving farewell to the Emirates. But there was something of minor statistical significance about the game, too.

Arsenal's thrashing of Burnley meant Sean Dyche's side were effectively condemned to finish the campaign with a negative goal difference, having spent the majority of the season with a positive record. That ensured that, by the season's end, only the "big six" finished the season with a "plus" figure. Everyone else conceded more than they scored; a telling portrayal of the Premier League: six good sides beating the other 14.

For context, over the past decade the number of sides finishing with a positive goal difference has generally been eight. A couple of times it's dropped to seven, sometimes it's risen to nine, and in that bonkers 2015-16 campaign with Leicester City finishing as champions, it was a healthy-looking 10, a 50:50 split between net scorers and net conceders. There has only been one previous example, in 1998-99, of only six teams in the positive.

You can consider this entirely irrelevant; statistical trivia with little direct impact upon anything tangible. But the numbers illustrate the fact this season's top flight was essentially two divisions: a top six and a bottom 14. And, from that secondary group of 14 sides, there was very little to choose between them. Burnley only managed 10 more points than a Crystal Palace side that appeared doomed.

That's the curious thing about this season's Premier League: the complete lack of "hierarchy" amongst the "other 14". The perception that there were several genuinely awful sides is actually entirely unfair. No one was as hopeless as last season's Sunderland or Aston Villa the previous campaign. But, at the same time, few sides have pushed on properly either: there's been no equivalent of Mauricio Pochettino's Southampton of a few years ago, or a Dimitri Payet-inspired West Ham.

There have basically been two different reasons for this pattern. The first is the underperformance of clubs who had seemingly established themselves as decent mid-table sides: West Bromwich Albion, Stoke City and Southampton were generally tipped for comfortable mid-table positions, yet comprised three of the bottom four (Swansea's struggles were less surprising).

Consistent mid-table side Southampton were one side who took a major step back in 2017-18. Alex Livesey/Getty Images

These sides evidently struggled with recruitment, either in terms of managers or players. West Brom's mid-season decision to appoint Alan Pardew was disastrous, while Southampton's choice of Mauricio Pellegrino last summer was similarly unsuccessful. Stoke's problem was more about poor on-field signings, as outlined in strong terms by Jack Butland after their relegation.

The second reason, though, is more positive -- several managers have worked miracles with relatively small budgets this season. The three newly-promoted sides -- Huddersfield, Brighton and Newcastle -- all survived. Burnley, generally considered one of the three favourites for relegation amongst bookmakers last summer, punched well above their weight. Furthermore, the early strugglers Crystal Palace launched an incredible turnaround under Roy Hodgson, and despite spending over half the campaign in the relegation zone, eventually finished comfortable mid-table. These managers -- David Wagner, Chris Hughton, Rafa Benitez, Dyche and Hodgson -- could genuinely all be shortlisted in the "manager of the year" debate.

So essentially, the sides we expected to be 5/10s were actually 3/10s. The sides we expected to be 2/10s were actually 4/10s. This has created a bloated mass of teams who have beaten one another, all been beaten soundly by the big sides, and made so many Premier League fixtures this season entirely unappetizing.

Next season the Premier League desperately needs more upwardly mobile sides, who can routinely beat bottom-half teams, break the 50-point barrier and offer something extra. This appears most likely to arrive if sides with slightly larger budgets and a recent history of finishing seventh or above (Southampton, West Ham, Everton and Leicester) appoint the managers who have worked wonders with smaller clubs. None of their current managers appear particularly safe, and the likes of Dyche, Wagner and Benitez might feel their talent is suited to clubs with more long-term potential.

The quality further up the league was unquestionably impressive. Manchester City were the most dominant champions the Premier League has witnessed in terms of points won, goals scored and their margin of victory over the second-placed side. Reaching 100 points had barely been imagined before this season, and Pep Guardiola achieved it with such a revolutionary, positive style of football too.

Indeed, the quality of managers at the top of the division is the single biggest reason for their current run of collective success. Jurgen Klopp's performance with Liverpool has also been excellent, albeit more in Europe than in Premier League terms, while Jose Mourinho has taken Manchester United to their highest finish since the Sir Alex Ferguson era. Mauricio Pochettino continues to overperform at Tottenham, while Antonio Conte's second season at Chelsea was something of a disappointment, but Chelsea at least reached a second straight FA Cup final.

These five managers can all be considered amongst Europe's most revered 10 coaches at the moment, increasing the margin between themselves and the Premier League's also-rans. Their good European performance Premier League may finish with more UEFA coefficient points than any other league (although there are still two continental finals remaining which may change things) for the first time since 2008-09. Whether that reflects upon the quality of the league overall, however, is questionable considering the huge gap back to the rest.

In truth, the 2017-18 season was amongst the most forgettable in the 26 editions of the Premier League. It didn't help that the title race was finished by December, but even more problematic was the lack of genuine tests for the bigger sides from the outsiders; the wet and windy night at Stoke was no longer a major issue, Swansea were no longer capable of outpassing big sides. There were few bottom-half players capable of providing a moment of magic to transform a game.

So what were we left with? Games between top sides and bottom sides were predictable, games between bottom sides felt unappetising, and games between the top sides were often irrelevant with the title wrapped up early. The Premier League loves to promote itself in terms of excitement and volatility, but this season was the entire opposite.