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.

Em dash = AI slop?

Punctuation as a giveaway

Recently, I've seen a lot of comments on the web that the use of em dashes is a dead giveaway that an article has been written by AI. This immediately made me think of my own use of dashes and semicolons.  I don't use AI for text generation, but I wondered if my writing might be mistaken for AI because of my use of punctuation. I decided to take a deeper look at the whole area.

(Gemini, with some assistance.)

Punctuation symbols

Let's start by looking at the symbols themselves.

Symbol	Name	Commentary
—	Em dash	Not easily available from my keyboard. Named because it's the width of a capital M. HTML: — Markdown: ---
–	En dash	Not easily available from my keyboard. Named because it's the width of a capital N. HTML: – Markdown: --
-	Hyphen	Available easily on my keyboard (minus sign)
;	Semicolon	Easily available from my keyboard.
,	Comma	Easily available from my keyboard.

Grammatical use

I'm not going to go into grammar too much here because I'm the wrong person to do that, but I will very briefly summarize the situation (my favorite grammar book is "Rules for writers" by Hacker and Sommers, check it out if you want a good grammar reference). Commas and semicolons have different grammatical purposes and their use goes back a long time. Hyphens are a more modern invention and seem to have some of the same usage of both commas and semicolons; a sort of generic punctuation mark. 

As far as I can tell, em dashes, en dashes, and hyphens are used for more or less the same grammatical purpose; they're interchangeable. Some websites suggest that there is a difference in grammatical use between — and – and these are reputable websites, so there may be some fine distinction. For most people and most uses,  em dashes, en dashes, and hyphens serve the same purpose.

Usage in the real world by people

Recent writing seems to favor the use of - rather than ;, especially in short form communications like text messages or even emails.  I've noticed some modern authors are using hyphens instead of semicolons, in fact, I've met a professional writer who always used hyphens and never semicolons. Overall, semicolon usage seems to be in decline.

If I'm typing in text, normally I only use characters easily available from my keyboard, unless I'm using a special character like a currency symbol (e.g. €). In other words, it's unlikely I'll use em dashes or en dashes. Given that it's hard to tell the different dashes apart, it's hard to understand why anyone (any human) other than a professional typesetter would use a dash other than a - (hyphen). In the sentence below, have I used an Em dash or an En dash or even a hyphen? 

"David lived in Paris 2005–2010."

It's hard to tell isn't it? Which means for humans, em dashes, en dashes, and hyphens can't easily be distinguished.

Is it a reliable AI detector?

Recent English usage seems to favor - over ;, so you can see why an AI might learn to use - rather than ;. As I said earlier, there are some websites that distinguish different uses between —, –, and -, so it's possible an AI will apply these rules too.  You can sometimes detect non-native English speakers because their English is too good, they don't make the mistakes native speakers do, and something similar may be happening here. An AI may be applying a "dashes" rule that a native writer wouldn't.

Is it a smoking gun proof? Probably not. I'm sure there are writers who love different dashes, and of course, the software they're using may convert hyphens into different types of dashes for them. But it is a strong indicator. 

I find distinguishing between dashes hard, but peeking at the underlying HTML or Markdown gives way the use of em-dashes and en-dashes immediately. So if you have access to the text, you can check.

By contrast, the use of a ; may indicate a human writer, until of course, AIs learn how to use it (im)properly.