Old & experienced vs. young and energetic: mean age in English football

Which is better, youth or experience?

Professional sports are pretty much a young person's game and English football is no exception; it's rare to see players over 30. One notable example is Mark Howard, a goalkeeper for Wrexham up to 2025, who was 38 at the end of his contract. His advanced age earned him the nickname "Jurassic Mark". He carried on playing as long as he did because his experience gave him an edge.

Given all teams are youthful, is it better to have an older team (guided by experience) or a younger team (the energy of youth)? Which type of team might score more goals? I'm going to explore this issue in this blog post.

(Canva)

The data

I've taken the data for this blog post from TransferMarket.com (https://www.transfermarkt.com/) that has data on the mean age of English football clubs at the start of each season. Obviously, transfers etc. change the mean age, but it's a reasonable place to start.

The charts

Here's a chart showing total goals for, against, and goal difference per season per club per league against mean team age at the start of the season. I've added a linear fit to the data so you can see the trends and I've included a 95% confidence band around the fit. The r² value is in the chart title, as is the p-value.

The charts are interactive, you can:

• Zoom in and out of the data using the menu on the left.
• Save the charts to disk using the menu on the left.
• See the data points values by hovering your mouse over the data points.
• Select the league tier using the buttons.
• Select the season using the slider.

What the charts show

There's some correlation between goals and mean team age, but it isn't very strong. 

For the Premier League, there is a consistent pattern over the years that younger teams do better, but it's a small effect, really something that's second-order at best.

For the lower leagues, again, there's an effect, but it's smaller and less consistent.

One thing that did surprise me was the consistency of the mean age ranges across leagues and across time. I would have thought that lower leagues might have more players towards the end of their careers (slower and cheaper) or possibly more younger players (inexperienced and cheaper) and that might skew the club mean age older or younger. That doesn't seem to be the case. It's possible lower leagues have a different club age makeup from the Premier League, but I can't get at that from this data set.

What does it mean?

A player might have ten years (ages 20-30) in the top flight if they're lucky, which suggests 25 is mid-career for most of them. At some point, they'll have an optimal balance between experience and youth, but that's unlikely to be at the beginning or end. A similar argument might apply to teams as a whole. If there's any truth to this argument, then some form of triangular fit would be better than a straight-linear fit. Even with the linear fit, we can see there is some relationship between goals and mean age, albeit a very weak one.

I'm looking for features that help predict team success. Club mean age seems like it would be a good second-order one.