Wednesday 6 March 2019

Title Winners Aren't Becoming More Dominant Over Time.

Are the title winning teams in the Premier League getting more dominant because they're getting so much richer?

It seems a logical conclusion to draw given that Manchester City won the league with an unprecedented 100 points in 2017/18.

That obviously makes them the highest points per game team in 20 team Premier League history, but without context, such figures are largely meaningless.

Taking the points per game high point as a selective cutoff point is invariably going to furnish any number of apparently positive trendlines, but without taking a deeper look at how the league as a whole has evolved over a period of time, they too are context-less trivia.

The first 20 team Premier League season in 1995/96 had 98 draws, by 2017/18 the number had 99. But singular seasons may hide an upward or downward trend and this appears to be the case with drawn matches and by extension the total points that were won in a whole season.

The 1990's averaged 104 draws per season compared to just 92 for the comparable number of most recent Premier League campaigns.

Here's what this means for the average number of points won by sides in each Premier League season since 1995/96.

There has been a steady upward trend for the average number of points won by all Premier League teams since the beginning of the 20 team era, as draws have tended to decrease, therefore reducing the number of matches where just two points are won compared to those where three are gained.

So are the top teams taking a bigger share of this expanded points pot, which may indicate that they are being more dominant that their predecessors were.

One way to look at this context corrected view is to see how remote the representative of each finishing position has become from the average points won by a side in a particular season.

Manchester City in 2017/18 were 2.5 standard deviations above the league average points won that season. But it's a level of dominance that was very similar to that attained by Chelsea in 2004/05, Arsenal in 2003/04 and Manchester United in 1999/2000.

Here's the plot of how far from the average points all 20 finishing positions have been since 1995/96.

OK, it's messy. But it's fairly easy to see that the title winners aren't powering upwards in a ever improving arc. In fact it pretty much flatline's and might even be encouraged to dip downwards if we wanted to be "creative".

Here's an easier on the eye trendline for each final position.

Once you add the context of the points gathering environment over time, Man City 2017/18 are just a bump in the road and not part of a general trend. None of the top three finishing positions have shown to have improved their dominance over the rest of the league.

There's been a slight uptick for 4th to 7th placed sides, a down tick for 7th to 12th. Then everyone holds station, until the two worst teams become slightly more competitive over time, but still go down.

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