How competitive was this IPL season compared to past seasons?

The IPL Playoffs start this week with the Mumbai Indians, Delhi Capitals, Sunrisers Hyderabad and Royal Challengers Bangalore finishing in the top four.

Going into the last round of the season, only the Mumbai Indians had confirmed their position in the Playoffs. And there was only one team, Chennai Super Kings, who mathematically could not make the playoffs. This meant that with just one round of matches to play there were still six teams in the running for the final three Playoff spots.

In the end, just a single win separated third place from last.The most aggrieved team will no doubt be the Kolkata Knight Riders, who finished in 5th, missing out on the Playoffs by recording a lower Net Run Rate (NRR) over the competition than Sunrisers Hyderabad and Royal Challengers Bangalore, who narrowly claimed the third and fourth Playoff position. These fine margins extended beyond just the Playoff race, with just three wins separating first from last - the least amount of wins separating top and bottom of the table in the history of the IPL.

We thought it would be interesting to compare this season to all the past IPL seasons to see which season was the most competitive. Looking at wins alone is not a sufficient metric as wins only give a binary outcome (i.e. you either win or lose), and does not take into consideration performance. Therefore, we have also compared the Net Run Rate of each team to give a better indication of the overall performance of teams across the tournament, beyond a simple count of how many victories they recorded (regardless of if they win or lose). The NRR is calculated by:

NRR = Average runs scored per over - average runs conceded per over

On the y-axis, we calculate the variation in wins from each season by taking the standard deviation of the wins for each team. The standard deviation is a measure of how much the values vary from the average value, which gives you an idea of how similar (competitive) each of the teams are in performance. For instance, if all teams had an identical number of wins, there would be no deviation from the average, therefore the standard deviation would equal zero. This would occur in a league that is highly competitive.

On the x-axis we show the variation in NRR. If there is a large variation in NRR, it would suggest there are stronger teams that have a considerably higher NRR than weaker teams, suggesting a less competitive league.

You can see that 2020 is quite isolated from the past seasons. It has a very small variation in wins (which led to the tightest table in the history of the competition) but actually quite a high variation in NRR. The primary reason behind a significant NRR variation is likely that MI recorded the highest NRR ever in a season at +1.107, considerably greater than Rajasthan Royals who had the lowest NRR this year of -0.569.

Across the 13 seasons of the IPL there seems to be a lot of variation in the competitiveness of the league. As the league is relatively young and with teams changing from year to year, it makes sense that some seasons are more competitive than others. However, it is interesting to note that 4 out of the last 5 seasons fall into the “competitive” or “highly competitive” range, which suggests that as the IPL matures, it is becoming even more difficult for the top teams to win the tournament. This is great news for the fans, as we should see plenty more thrilling battles at the top in years to come!

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