22 October 2019, by: Laduma Analytics

PSL Analysis: Age Profiling PSL Strikers

Our next series of articles examines positional profiles in the ABSA Premiership; starting with Strikers. Using data from InStat, we examine how 1) the statistical output of Strikers has changed during the past few seasons as well as 2) how these metrics have changed as well as the age of the position.

It is fair to say that as humans ‘grow’, we physically (and mentally) mature as we get older. Inevitably, we also begin to lose some of this acquired physical presence. When this occurs is often up for debate and something we will not be discussing in this series. What we are however interested in is how/if positional requirements have changed in the past few years and whether PSL clubs should consider this when building their squads.

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Using the InStat database which has data on matches, players and teams; we used all available player data from the 2015/16 to 2018/19 season. In addition, only players who played more than 1,000 minutes throughout a season were included in the analysis.

The series of graphs below have an added width to their lines; where the line is thicker, the greater number of players in that current age bracket are present. We also acknowledge that said players often transfer between positions and as such have left players in their ‘allocated’ positions from the database.

Over the past few seasons, the age profile of forwards in the PSL has become much younger than before.

In 2015/16, the age spectrum of a PSL striker varied from 21 to 39 years of age with the majority of minutes given to players between 28 and 33 years of age. The youngest player that season was Phakamani Mahlambi who played ay Bidvest Wits and now plays with Sundowns.

During that season, he scored 4 goals and assisted 3 more bringing his ‘scoring contribution’ to a goal/assist every 138 minutes he played for Wits.

Fast forward to 2018/19, the age spectrum has decreased to 34 years of age with most minutes played going to strikers of 28 to 30 years of age.
When it comes to how fans evaluate a striker’s contribution to their team, opinions can widely differ. One common factor that often gets discussed is how ‘often they score or should score’.

Little to no regard is placed on other aspects such as creative play, tackling or even space creation. If we break down the shooting numbers by season, we can see that while there may be some discrepancy issues with the data in 2016/17 (not all clubs were signed up to InStat at the time), PSL strikers are ‘generally’ getting better at ‘hitting the target’.

How or why that is, would need further examination but one could assume that strikers are generally closer to the goal and thus ‘hit the target’ more often than their team-mates. If this is indeed true, it would be valuable to know who these strikers are, what sort of positions they get into and how they convert their chances.

Unfortunately, as already specified…that is currently not available. What was available, the number of shots taken in comparison to another metric known as ‘scoring contribution’ (Goals & Assists). We broke these two metrics down further into ‘what would we expect the average PSL striker for a specific age range to contribute over 90 minutes’.

How or why that is, would need further examination but one could assume that strikers are generally closer to the goal and thus ‘hit the target’ more often than their team-mates. If this is indeed true, it would be valuable to know who these strikers are, what sort of positions they get into and how they convert their chances.

Unfortunately, as already specified…that is currently not available. What was available, the number of shots taken in comparison to another metric known as ‘scoring contribution’ (Goals & Assists). We broke these two metrics down further into ‘what would we expect the average PSL striker for a specific age range to contribute over 90 minutes’.

What is immediately noticeable is the rapid decline of shots taken in the early stages of a Striker’s PSL career. The number of shots climbs and falls as players go through their late twenties and early thirties. This trajectory differs slightly to that of research conducted by analysts such as Colin Trainor on the Top 5 European leagues.

The scoring contribution though generally stays constant until the latter years of a strikers’ career and agrees with the research conducted by Trainor above. Does this mean that the days of a Musonda are behind him – not necessarily but his opportunities are limited. It may also explain why we as South African fans saw a high-flying Percy Tau before he made his move to Premier League side Brighton & Hove Albion in July 2018.

Next up, we take a look at the quality of the shots taken. Using another metric known as ‘Expected Goals Per Shot (xG per Shot)’, we can examine a striker’s shot quality. Generally speaking, the higher the value, the better the quality of the shot.

Without getting bogged down into the statistical values, the same methodology was applied as above. The number of shots a player takes and the quality of these decrease dramatically over the lifespan of a PSL striker. Even where most players are represented (between 28 and 33), their shot quality is only average and then nose-dives before one or two ‘golden oldies’ resurrect the chart one last time.

Within this average pile, it is worth scouting which players stand out. We remember doing a scouting piece on Mwape Musonda over the summer and his expected shot quality was approximately 0.12/0.13. Why did he not move to a bigger club you ask? He was pretty one-dimensional from a statistical stand-point and therefore a risk for a bigger PSL club.

There is more to a striker’s/player’s game than just shooting, scoring and assisting. How they move, where they move, how they interact with play or how they pressure the opposition when out of possession (to name a few metrics) should all be considered.

Also, where a striker sits on his career trajectory in accordance with the research would be beneficial for transfer and style of play objectives. Let’s take a look at the next metric: Chances created.

The 28-year-old age bracket is again heavily populated and features names such as Gaston Sirino & Khama Billiat. Without sounding too obvious, both players create several more chances than the average PSL Striker (which is most likely due to their respective team’s style of play) and for their age respectively.

Who were the youngest & oldest players for chances created last season? Jemondre Dickens (Baroka FC) & Eleazar Rodgers (Free State Stars; now Ajax Cape Town). As with the other metrics observed thus far, the age of a striker matters when the output is examined. The level of chances created by PSL strikers is on a fairly high decline and yet the sample size around 28 to 32 adds some perspective or possibly just noise.

Therefore, if you are charged with the recruitment of players and your club that relies on your striker to contribute to the creation of chances for team-mates, looking for younger talent may be more beneficial.
The same approach can be taken when examining the number of Dribbles that PSL strikers attempted and successfully executed over the career timeline.

In terms of passes attempted, the numbers were very consistent. PSL strikers along their career timeline attempted approximately between 21 and 24 passes per game whilst the only brief inconsistency came between the ages of 26 and 29 where passes attempted were at lows of 14 to 18 passes per game.

We acknowledge that this concept of Player Aging is not a first for football fans, however, we wanted to examine the constraints placed on strikers at different ages in their career. Whether this analysis will provide any changes to how a PSL team will structure it’s starting eleven or its squad going forward is an interesting project.

Ideally, this analysis will give some sort of benchmark for clubs to discuss how the up and coming youngsters are utilised at the highest level of domestic football in South Africa.

These findings are not final and rather a guide for further exploration of how and why some players can maintain performance levels higher than others.

Thus, based on the data available and represented in this analysis, the ‘peak’ age for a striker to be applying his trade in the PSL ranges around 25 to 28 years of age. In our next segments, we will examine Midfielders and Wingers.

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