It’s the 900-minute klaxon.

This ‘magic number’ is the minimum playing time I use before the dataset associated with a player becomes meaningful to analyse. It works out as the equivalent of ten full matches. In that time, I believe a player reveals himself as regards strengths and weaknesses. That is not to say that they will not develop and improve or even regress. It is very much a point in time.

Passing that threshold is summer signing Hyun-Jun Yang, a winger signed from Gangwon in South Korea for £2.1m. Yes, I had to sit down too.

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Yang has been thrust into the starting eleven mainly due to injuries to Liel Abada and Daizen Maeda. He has yet to complete a full 90-minute game but appeared in nineteen matches, starting eight. Maybe it was never the intention to lean on Yang quite so much this early into his Celtic career but now compromises are being made across the squad.

So, here we are and here’s the data summary. I am comparing Yang to Abada, Maeda, Jota and Sead Haksabanovic from last season.

Chance creation

A Celtic wing-man’s job is multi-faceted, but a core requirement is creating chances for the striker and other attacking players.

Firstly, we’ll plot expected assists (xA) from open play (to remove the impact of set pieces which pad out data for some players) and the number of passes completed into the danger zone (in the box central to the goal).

Not an auspicious start as Yang maps below Maeda. Maeda has many qualities, but outright creativity is probably not a core one. His role is to bother defences mercilessly without the ball, then stretch defences in behind when Celtic have the ball. He is a good finisher too.

Yang is more of a traditional winger. He seems comfortable taking people on and running at defenders. What this shows is we are simply not seeing enough creative passes in the final third. He profiles a LONG way from the performance of the wingers last season.

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Remember Haksabanovic and Abada were largely impact subs, perhaps the role Yang was earmarked for this season. My own observation is that whereas Abada, Jota and Haksabanovic tended to see a cross into the box as a pass with control and an intended target, Yang seems to work a yard then simply bang it into an area.

Unfortunately working with a striker like Kyogo Furuhashi – a smaller forward - a precision of pass is needed to match his precision of run. So far this season, Yang has provided just two passes to Kyogo that have resulted in shots for the Japan striker.

Goal threat

Speaking of goal threat, Celtic’s wide player contributed 44 goals with three of them in double figures. So far Yang has one versus Aberdeen. But we know xG is more predictive of future performance.

Yang’s non-penalty xG so far is below 0.2. Last season of all the midfielders and forwards who played more than 900 minutes, only Callum McGregor - the holding midfielder - had a non-penalty xG lower than 0.2.

He is averaging 1.52 shots per game which is the lowest of this peer group and his average xG per shot is 0.12 which only Haksabanovic fails to achieve. This is despite averaging 5.43 touches in the opposition box, higher than Maeda and equivalent to Jota and Haksabanovic. This simply isn’t productive enough in a dominant side like Celtic.

Deep progression

Sometimes players are better at deeper link-up play. We can assess this using the pack passing score (this reflects the number of players you take out of the game with forward passes) and expected assists generated from secondary passes. The latter are passes to the person creating the chance.

Yang profiles better here than Maeda. Maeda is not a creative player in any sense other than forcing opposition errors. The others are all players who try and bring others into play and attempt risky passes into the final third.

Yang actually provides a better quality of secondary assisting pass than Jota, but Jota was very much a final-third volume player. The more direct comparison in terms of squad place would be Haksabanovic. Maligned by some, but his deep creation is on a different level from Yang.

We’re not finished with Maeda just yet…

Defending

The Japanese first-choice striker is a defensive monster for Celtic and leads the pressing stats by some distance. Meaning - above and beyond attacking nuances - he has utility in that quite specific role.  But there is no doubt the defensive side of the game is part of the wing play.

Yang profiles well by the defensive measures. He is second to Maeda on defensive actions won and possessions won from defensive actions. He is also third in pressures per 90m with 14.04. Yang also leads this peer group in winning the ball back in both Celtic’s and the opponents' defensive thirds.

Whilst not as strong as Maeda, he perhaps has some development as a hard-working ‘defensive’ winger. You can see why Brendan Rodgers has given him game time in European matches as the 'working back' elements that perhaps Mikey Johnston struggles with, Yang covers well. A ray of hope for the South Korean winger.

Wastefulness

Until that is, we consider the question of how wasteful a player is with the ball.

I measure this by plotting the number of times they lose possession in the final third (i.e. without a shot, a chance, or otherwise maintaining possession) and the total number of times the player is dispossessed anywhere on the field per 90 minutes.

This view is quite damning, as the peer group are clustered towards the middle, and Yang is a clear outlier in terms of the sheer volume of times he loses the ball in general and specifically in the opponents’ final third. You can think of this as a proxy for decision-making and for technique under pressure. Yang is simply too wasteful in possession and as can be seen above, the ratio of number of quality of chances and shots created/taken is not offsetting this profligacy.

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Jota was high volume, meaning he tried a lot of passes and shots meaning there was a lot of dross and failure but in amongst that were many great passes and accurate shots. With Yang, the trend is too much towards waste and not enough towards productive output.

Summary

Yang profiles as a very raw recruit and does not seem ready for Celtic first-team action.

He shows signs of being effective without the ball in terms of pressuring the opponent and in his ball-winning capabilities across the field. However, his overall attacking productivity is of insufficient quality to offset how wasteful he is with possession.

This encapsulates how the quality of the Celtic squad has been reduced in this critical season, where £60 million of Champions League money is on the line.