By Andrew Puopolo
You often hear television commentators compare teams to their bitter rivals to illustrate its current status. Over time, the nature of rivalries changes due to each team’s movement between divisions. Some teams (like Arsenal with St. Totteringham’s Day) often directly compare themselves to their bitter rivals.
I wondered if there was a correlation between the league position of a team and their rival from year to year (positive or negative). To do this, I compiled a list of the 20 biggest rivalries in English Football. I chose 16 of these rivalries from a 2015 Telegraph article and discarded 4 on the basis that one or both of the teams involved had spent considerable time out of the Football League. I then picked 4 additional derbies (Manchester United-Liverpool, Tottenham-Chelsea, Manchester United-Leeds, Preston-Blackpool) out of my own personal curiosity.
I then calculated the correlation between the league positions from the 1958-59 season through to the 2015/16 season. If a team finished 5th in the Third Division, their league placing is defined as
5 + # teams in First Division + # teams in Second Division
The 1958/59 season was chosen as the start date because that was the first season after the Third Division split from being North and South into a Third and Fourth Division. The correlations between each of our rivalries are below.
A few things stand out:
There was no strong correlation to be found, suggesting that neither a positive nor negative relationship exists
Between the 20 derbies, there was an average correlation of .08 with standard deviation of .28. Some derbies showed some small level of positive correlation while others showed small level of negative correlation. In the end, there isn’t enough evidence to conclude that there is a level of correlation on the whole.
The Media have got it slightly wrong when portraying the Chelsea-Tottenham rivalry
In recent years, whenever Chelsea have played Tottenham Hotspur, the media often spins the familiar narrative along the lines of “Spurs used to be the more successful team, winning with stylish football in the 1960’s, but in recent years Chelsea have overtaken them with spending power and won many trophies of their own in the last 15 years, sometimes at Tottenham’s expense.” This would imply that there is a negative correlation between Tottenham and Chelsea’s league positions but the data suggests otherwise.
The same narrative also doesn’t hold up with the Liverpool-Manchester United rivalry
The media also have a similar party line when referring to the North West derby between Liverpool and Manchester United. Whenever the two meet, the media often reminds everyone that Liverpool were the team of the 1970s and 80s, winning 11 titles in 15 years in addition to 4 European Cups, but Sir Alex Ferguson at Manchester United was determined to knock “Liverpool off their perch” and since Liverpool’s last title in 1990, Manchester United have won 13 titles. This also would imply a negative correlation, but like with Chelsea and Tottenham, our data shows that there is almost no correlation between the two clubs’ league positions.
The correlation between Swansea and Cardiff is likely due to their unique position in English Football
The only derby we had that showed a medium level of correlation was the South Wales Derby between Swansea and Cardiff. The two clubs are the only 2 clubs from Wales that have regularly played in the English Football League system and are therefore are subject to the same challenges with regards to assembling their teams. Any change to the Anglo-Welsh relationship affects both of them equally and no one else so it makes perfect sense that this rivalry would have the highest level of correlation.