BEWARE a system. Beware a philosophy. Beware falling into the trap of thinking that you’ve cracked the Premier League. 15% of the division will disappear every season, no matter what else happens.

Newly-promoted Norwich and Aston Villa may well be two of those sides in 2019-20 and if so, nobody will be too surprised. Joining them, though, could be one of Bournemouth (promoted in 2015), Watford (also promoted in 2015) or Burnley (promoted in 2016). Those three clubs do not share a common philosophy but at various points in the last few years a case has been made that they are established, even though, while relegation is still a part of the Premier League’s structure, they absolutely are not. Even Arsenal (back in 1912-13, fact fans) have gone down.

Those clubs just have to look at the likes of Stoke City and Swansea before them, both of whom came up, and in very different ways, weaved themselves into the short-term fabric of the Premier League. Stoke had their towels, their long throws and their dislike of Arsenal, while Swansea had Leon Britton, Passalona and aggressive middle-aged ballboys. Stoke lasted 10 seasons, Swansea seven, but both eventually succumbed to what some know as Charlton-Athletic-itus, a condition where a mid-ranking Premier League team has to counter ennui with a plan for continued progression but by doing so they end up losing the very status they had worked so hard to achieve.

Charlton in the early and mid 2000s had finished 9th, 14th, 12th, 7th, 11th and 13th and had dreams of Uefa Cup qualification, but instead crashed out of the division in 2006-07 and have not returned since.

So that’s the overarching pattern, but just as no Premier League club has the same philosophy as their rivals, there is no single reason a side will succumb to the inevitable death rattle of the drop. If we take Burnley then it seems that whatever defensive magic got them to seventh place in 2017-18 (a season in which they scored only 36 goals, just one more than Stoke who finished 19th) has run its course.

That season Sean Dyche’s team faced 570 shots, and had an Expected Goals against figure of 52, yet conceded only 39 goals and (I feel I should reiterate this) finished in seventh place. That sort of overperformance at the back baffled observers and models (data models, not the fashion industry) and there was cosmic relief in 2018-19 when Burnley returned to average.

And, as the graphic below shows, this season is very much the reverse of 2017-18. Burnley’s xG against this season is only 29, roughly level with Arsenal, but they have let in 37 goals. “You’ll never be able to completely explain football with numbers” they say. Yes, true, and teams will continue to get relegated out of nowhere. Like light reaching Earth from a star that died millions of years ago, we can see the way things are going for Burnley, but there is nothing we can do to change the inevitable.

Pivoting to Bournemouth, there is little point looking at their defence in much depth, given their four completed Premier League seasons have seen them concede an average of 66 goals. In 2015-16 Eddie Howe’s team let in 67 goals and came 16th; 12 months later they let in 67 and came… ninth. This season they are on course to let in 61 but much more importantly, no team has scored fewer goals than the Cherries.

The King/Wilson input that has served them so well in previous campaigns has simply dried up. Callum Wilson has now played 1,021 minutes of Premier League football since recording a shot on target, a period so long you could watch the final two seasons of Game of Thrones back to back and still have 71 minutes to do something else (make some food, presumably).

The gap between Bournemouth’s actual goal total and their xG is minus 3.6; as it stands only three clubs have a bigger negative gap but they are Watford (appointed a new manager and are now good again), Southampton (didn’t appoint a new manager and are now good again) and Everton (appointed a new manager and are probably good again). Can you sum up how big Bournemouth’s trip to Norwich is this weekend in a word? No. In a sound? Probably yes [Woouueerrrr].

In summary, then, no club, except maybe Derby County in 2007-08, actually seeks out relegation but it’s always there in the background, quietly waiting. It’s probable that a relatively-long serving Premier League team will go down in May and someone involved will say something like “we never saw it coming.” Well we did see it coming, we’ve seen it before and we’ll see it again. You might be able to outrun your opponents but you’ll never outrun the numbers.