Examining the Relationship Between Teemu Pukki's Hair and His Effectiveness at Norwich City

Minnesota United are reportedly working to sign Finnish striker Teemu Pukki. Pukki, 33 years old, comes to MLS after an extraordinary five-year stint at Norwich City in England, where he was one of their most prolific goalscorers ever. He ranks 4th in club history in goals, only trailing Iwan Roberts among players whose careers occurred within the last 50 years. Additionally, he is the top scorer in the history of the Finnish national team. He is as beloved a Canary as they come, as demonstrated by the ovation he received in his final game this May.

Supporters will miss him deeply, even if his successors manage to approach Pukki's greatness. I speak firsthand: As a Norwich fan, even one on a different continent, I've so appreciated his intelligence, hard work, and clinical finishing, which was never better showcased than with Emi Buendía on his right wing. Though Pukki is too short to be a traditional target man, there are few better at playing off a defender's shoulder and perfectly timing his run onto a through ball. Buendía was the perfect partner, assisting Pukki on 16 of his 88 Norwich goals. In the 2020-21 title-winning season, with Todd Cantwell completing the Norwich front three, they combined for some of the prettiest stuff the Championship has ever seen.

Pukki has been analyzed plenty: his traits on the pitch, his best goals, where he ranks among Norwich's greats, and what could have made his Premier League stints more successful.

Today, we're going to talk about his hair. Like other athletes I've written about here, Pukki doesn't have a lot of it. This wasn't always the case; in his younger years, Pukki sported a thick, unkempt shag. But by the time he arrived in East Anglia at the age of 28, his hair was starting to thin, and he's since had to keep it short, if not shaven. Sometimes, he has gone long stretches without a cut. He's also sported a beard, which he sometimes trimmed and regularly let grow all the way out.

What we are here to do is find a connection between the amount of hair he had — on the top of his head or on his face — and his scoring proficiency in a Norwich shirt. This is important work.

I have attempted to define his beardedness and baldness on a four-point scale, and divided his shooting and finishing statistics based on those ratings. It's not totally scientific, since there are grades within each of the grades I've identified, and even discerning which rating applies is hazy. I couldn't always find clear photo or video for a given game, which meant had to base my decisions for that game on a few frames from a 4-minute highlight reel. Weather, lighting, and video quality probably led to a few misclassifications. But over the course of Pukki's five seasons, I think those judgement calls balanced out, and we can find some trends.

Here is the key I created for myself on this totally serious investigation.

By far the part of this exercise that had the most grey area was when I had to figure out whether Pukki's haircut was a 2 or a 3. Generally, if it could look from a distance that he had a full (if buzzed) head of hair, it was probably a 3. At a shorter cut, his balding pattern is a little less evident, but as it grows out it becomes clear how perilously Pukki might approach the McClaren Zone if he grew out his hair all the way again. The point where that front patch became a little more defined was another indicator, if I could identify it with the available images.

On Pukki's beard, there was less ambiguity. The only question mark was at what point a 3 became a 4. If it was so grown out it became wild, with the hairs straying farther from his jawline, then I classified that as the Finnish pirate. There were only a handful of these cases, which suggests the bar may have been too high.

I have also concocted two stats based on the hair and beard numbers: the follicle ratio, the ratio of hair-to-beard rating for a given game, and the follicle index, the sum of his hair and beard ratings on that day. When I first tweeted this idea into the wild, I framed it in the context of Pukki's scoring improving when he has less hair, so we can use the follicle index to measure that hypothesis.

One more note: I only used league games that Pukki appeared in for Norwich. Though it might have been more comprehensive to include cup matches (or even friendlies), detailed stats are harder to find outside of league competition. Sticking to Championship and Premier League matches still gives us a roughly 200-game sample.

Here is a raw breakdown of our data.

Click to enlarge.

The first thing to point out is that Pukki never played a game for Norwich clean shaven. In his first couple of seasons, he grew out his hair all the way, but he always had at least a noticeable stubble, if not a full beard.

While Pukki let his beard grow more over the course of his career, 3 was his most common beard rating in each of his five seasons. There was a bit more variety on the top of his head, though.

Pukki never shaved his head entirely in his debut season, but that gradually became his second-most common look, including in his Carrow Road farewell this May. By the end of his time in yellow, he never let his hair grow all the way out. The thickest it ever got in his final three seasons was a 3. 2s and 3s became his most common looks for the back half of his career, accounting for about 90 percent of his minutes in the 2021-22 season.

But what of Pukki's effectiveness in each state of beardedness or baldness? There are a good few ways we can measure performance for a striker: how many shots he is able to get off, how many he gets on target, the quality of his chances (measured in expected expected goals), his scoring rate, and how many more goals he scores than expected of him based on the quality of those chances. Where applicable, we can look at each of our metrics on a per-90-minutes basis.

To the first measure: Pukki's shots per 90 were fairly constant, regardless of how much hair is on his head or face. Across his Norwich career, he averaged 2.9 shots per 90. When broken down by any of our variables, there isn't much derivation from this overall average, aside from a couple of follicle ratios that he sported only in small samples. We can attribute any variation to noise here.

We can start to see more of a trend, though, when we move to Pukki's on target rate. His beard seemingly had little to no influence over whether the shots he took were on goal. But there's a noticeable jump — between 10 and 14 shots per hundred — when Pukki was clean-shaven.

This cannot be attributed to a few outliers. Of the six matches in Pukki's Norwich career where he recorded at least four shots on goal, just one (2021 vs. Reading) was a game where he was clean-shaven. (The others were all 3s on the hair scale.)

This jump is not apparently the result of changing shot quality, either. His expected goals per shot attempt appears largely independent from his grooming — his shot quality while bald saw a noticeable increase, but not one large enough to entirely account for his leap in accuracy.

No, it appears that a baldheaded Pukki was more dialed in. Perhaps he benefitted from not being weighed down as much by a head of hair. A more aerodynamic Pukki was a more clinical Pukki, as indicated by his conversion rate — both on all shots and on shots on target specifically.

Our lowest follicle index in the sample, a 3 (a bald head and trimmed beard or stubble) is admittedly Pukki's lowest-performing by expected goals and conversion rate. However, Pukki only played 419 minutes with that ratio, equivalent to less than five complete matches. A follicle index of 4, meanwhile, is the best performing: Despite being at that level of hairiness for just over a tenth of his minutes in a Norwich shirt, Pukki scored 18 percent of his goals while playing with an index of 4. He outperformed his expected scoring total by nearly six goals. While he was always an effective finisher for the Canaries, he was ruthless in front of net when there was less hair on him.

This study is not perfect, of course. As mentioned, differentiating between grades of hair or beard thickness was an imprecise process. A more thorough examination of this question would find a way to control for quality of opponent, or take into account Pukki's track record at Brøndby, Celtic, and Schalke, or with Finland. (This would require more detailed statistics than are publicly available.) Any way to expand the sample and account for other variables is likely to be more informative.

But the general lesson we can pass along to the Loons is this: If they complete the signing of Pukki and want to get the most out of their new striker, they must also find someone who can fill Grant Hanley's shoes at the barber's chair.

Q: At which fancy establishment did Teemu Pukki get his hair done ahead of Finland Athlete of the Year ceremony?

A: In the washroom at #ncfc training ground with Grant Hanley wielding the clippers. pic.twitter.com/Jmtn67oFiu

— Chris Goreham (@CGoreham) January 19, 2020

Actual statistics (minutes, goals, shots, shots on goal, xG) via FBRef.com.