The concept of fixture rotation is nothing new. It’s been discussed on this site and others for years. This article will unpack data from the 2018/19 season to quantify the theoretical value of the typical home/away rotation (punchline: it isn’t much), and suggest an alternative approach.
The Concept
For the uninitiated, a rotation strategy simply means selecting two players (typically lower stature defenders or goalkeepers), and rotating them based on the home or away fixture. Each year there are several pairs of teams which rotate perfectly (e.g. when one is home, the other is always away), and these pairs are typically the target of the rotation strategy. The idea, of course, is to always capture the home field advantage.
The Data
Because rotation strategy typically involves defenders and/or goalkeepers, I am going to focus on clean sheets for the purpose of this analysis. As the tables below show, over the course of the 2018/19 season there were 207 total clean sheets out of a possible 760 (38 matches x 20 teams) or 27.2%. Of the clean sheets, 57.5% were kept at home, while 42.5% were kept away. Said another way, the “average” team kept a clean sheet 31.3% of the time at home and 23.2% away, with an overall clean sheet percentage of 27.2%. That idea is illustrated in the bottom row of the right hand table.
That isn’t the whole story, however. As one might expect, the top six sides capture a disproportionate share of the clean sheets. Since top six players aren’t typically used in a rotation strategy, it’s important to filter them out. When you do, you see that the average non-top six side kept a clean sheet 27.1% of the time at home and 22.9% of the time overall. Those key numbers are in orange and green.
Home/Away Rotation Punchline
From here, quantifying the value of the rotation strategy is fairly straight forward. The average non-top six side is expected to keep 22.9% * 38 games or 8.7 clean sheets. Using a perfect home/away rotation, one would expect 27.1% * 38 games or 10.3 clean sheets. Assuming 4.5 points per clean sheet (which gives some arbitrary credit for BPS), the expected value of the strategy is (10.3 * 4.5) – (8.7 * 4.5) or about 7.2 points! That’s a paltry total. I’d say those who shun rotation are rightly skeptical.
Case Closed?
So, rotation is dead, right? Not so fast. What if there were pairs of teams, which when rotated, never play a top six side, or better yet, always play a bottom half side. Would that change things?
The Data
The analysis for this part is a little more nuanced, but still rather straight forward. If you look at non-top six sides (remember, we are doing that because those are our rotation candidates) playing against bottom 10 sides, there were 130 such games last season, meaning there were 260 clean sheet opportunities. There were 81 clean sheets in this group or 31.2% of the total opportunities, as shown in the table below. Please note the home/away percentages are irrelevant for this section, but I have included if you are interested.
Fixture-Based Rotation Punchline
As we saw in the earlier analysis, the average non-top 6 team kept a clean sheet 22.9% of the time, which yields an expected clean sheet total of 8.7. Using a perfect fixture rotation, one would expect 31.2% * 38 games or 11.9 clean sheets. Using the same 4.5 points per clean sheet, the value of the strategy is (11.9 * 4.5) – (8.7 * 4.5) or about 14.2 points. That’s still not great, but it’s twice as valuable as the home/away rotation.
It turns out there are two team pairs with nearly perfect fixture rotations this season. Those pairs are Everton/Crystal Palace and Wolves/West Ham.
Their fixture rotations can be seen here.
Even that has problems. For example, rotating West Ham and Wolves keepers will cost you 10.0m, and for that you are better off with Ederson or Alisson and a 4.0. Same problem with Palace and Everton (and potentially worse depending on who actually starts for Palace).
As an aside, it’s worth noting that Wolves/West Ham also have perfect home/away rotation. Sadly, these don’t overlap. That would be a unicorn indeed.
Conclusion
Using 2018/19 data, home/away rotation is of dubious value, generating an expected additional return of just 7.2 points, based on clean sheets only.
Fixture-based rotation is better, generating an expected additional return of 14.2 points, again based only on clean sheets.
Neither strategy generates massive returns, and for the money, set and forget options may be better.
4 years, 9 months agoThank you for posting 🙂
I'm a fan of fixture based rotation pairings but currently looks like I'll start with neither this year due to the way the teams that could rotate are priced. I'm happy to see the maths backs me up there 😉
I might end up with a Villa / Burnley rotation, though I'm not sure how long that would last me and based on the above, if it's worth it!