Since 2000-01 there are three teams that have finished in the top half of the league one year and been relegated the next. I’m going to take a look back to determine if there are any obvious reasons that explain the demise.
West Ham United
First up is West Ham, a case of an average team getting poor luck. Whilst their play in 01-02 was sustainable going forward (sensible PDO) their goal difference didn’t warrant the number of points they scored and to an extent they were in a false position in the league. Entering 02-03 it would have been reasonable to expect a 10th-15th place finish but a decent performance (.486 SOTR) was outweighed by bad luck (low PDO) and they were relegated, despite scoring 42 points. A PDO of 1000 would have seen them score around 8 extra points and finish 11th.
Reading entered the premiership having scored 99 goals in getting promoted from the championship and scored 52 goals in their first premiership season (one of only 5 promoted teams since 2000 to score 50+ in their first premiership season). Their second season wasn’t quite as enjoyable and the team was ultimately relegated on goal difference.
It’s pretty easy to see what happened here. In 06-07 Reading rode an incredible amount of luck(a PDO of 1123 is amongst the highest ever and simply unsustainable). In reality they weren’t a very good team (very poor SOTR) and whilst their PDO gained them ~16 points in the league and kept them out of a relegation scrap the first time around, it regressed to the mean in 07-08 and they were duly relegated.
In the 2000-01 season Ipswich were a genuinely decent team (only ‘the big four’ and Spurs have ever posted a higher SOTR) and their relegation in 01-02 is easily the biggest surprise of the three. Entering 01-02 it would have been reasonable to expect a top ten finish but a combination of two factors led to them being relegated. The first was a significant drop in the teams SOTR from very good to below league average. In 01-02 they were very similar to the West Ham team in 02-03. The second factor was a large drop in PDO, to an unsustainably low 909, costing them ~13 points and their premiership status.
So what causes a top ten team one year to be relegated the next? Well Reading weren’t a very good team the first time round and we could have predicted they would struggle just by looking at their PDO value for 06-07*. West Ham were an ok team who were simply victims of luck and whilst a bottom half finish wouldn’t have been surprising there aren’t any big clues to suggest that team would go down. Ipswich were a great team but were relegated because they became merely average and then got some terrible bad luck, that is one no-one would have predicted based on stats.
*in fact the drop in PDO was largely due to Readings shooting percentage. In 2006-07 they had a sh% of 30.59%, 2 standard deviations above league average and amongst the highest of all time. In 2007-08 this regressed to a league average value (21.47%), a 9% fall.