The Rogic Celtic factor Turnbull must try to replicate

A similarly placed and aged squad member, David Turnbull, found himself marginalised near the end of Ange Postecoglou’s stewardship. Like Welsh, the midfielder is important in that he contributes to the home-grown count of players in the squad. Celtic are at risk of having a depleted Champions League squad if they cannot meet the eight home-grown player quota.

There is, therefore, a premium on such talent, and you would imagine all such categorised players would get a chance to shine. Remember that in Postecoglou’s first season, Turnbull was mission-critical in the early stages of the campaign. He started the first 33 matches of the 2021-22 season. Arguably he was overplayed, and as a result, he broke down in the League Cup final against Hibernian and started just two more matches after that.

In 2022-23, he made 38 appearances but only completed 90 minutes twice and had just 10 starts. The recruitment of Aaron Mooy, who flourished, plus the improvements in Reo Hatate’s game, meant Turnbull ended fifth choice for the two number eight spots with Matt O’Riley a virtual ever-present.

Turnbull v Turnbull

How does the Turnbull that started as a first-choice pick until the League Cup final match up versus the substitute version from last season?

Considering the differences between starting and coming on as a substitute – normally when Celtic are well ahead, and there are relatively fertile opportunities for stats padding – the radars are quite similar.

Where Turnbull improved greatly is in defensive actions with significantly more tackles and interceptions last season over the previous campaign. This may be because of the improved team cohesion as regards the pressing and counter-pressing patterns and trigger responses.

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In the season that has just finished, it has probably been difficult for Turnbull to improve radically by coming off the bench and averaging just 32 minutes per appearance. With Mooy retiring and some speculation concerning the future of Hatate, can Turnbull potentially reinstate himself in the starting XI? Also, does the signing of another central midfielder in Odin Thiago Holm affect his future?

Turnbull v other number eights

Let’s consider how Turnbull measures up against his peers over the last two seasons.

Defending: 

Using a defensive assessment framework, it is clear that each of the number eights are plotted close to each other, but there is quite a range of defensive performance. O’Riley is clearly the most active and effective defensive performer and Mooy was very close to his level last season. Hatate’s provides much less defensive output and his performances improved very slightly season over season.

Turnbull, although contributing more tackles and interceptions, is by some distance less defensively active than the other number eights.

Creating: 

These plot open play expected assists with pack passes – forward passes that take opponents out the game. As well as illustrating how important Mooy became to Celtic, it is clear Turnbull is creative for the Hoops over and above his excellent set piece delivery. 

In the 2021-22 season, it was his ability to pick through the defensive lines, whilst last year, his was an expected assist rate close to 0.45. Remember, there is the 'sub-dividend' factor for Turnbull. That is, there is clear evidence that those coming on late in games benefitted from an xA and xG rate higher than the starters, given the impact of a dominant Celtic and their squad depth against tiring opponents.

Goal threat:

Mooy’s goal threat is reduced when penalties are removed. But again, Turnbull provides the most goal threat of the nominated eights both in terms of volume of shots and chance quality, as expressed by xG. O’Riley is worthy of note as he played 12 matches as a holding midfielder in last season yet ended up with the highest overall non-penalty xG from open play of that group.

Summary 

What to make of all that? Well, let’s go back to how Brendan Rodgers wants his midfield to look. "More power and more flexibility." were his words at his unveiling. It could be argued that Turnbull’s main weaknesses are power and pace and his defensive numbers reflect that. 

As regards flexibility, although he has performed well as a number eight in Postecoglou’s system, he profiles more like a classic number ten with his creativity and goal threat. Will Rodgers play with such a role as he did in his first spell with Tom Rogic?

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Mooy’s retirement complicates things, as does the home-grown rule. A further unknown is whether Rodgers goes with two eights or two deeper players and a number ten. If the latter, then there could be an argument for Turnbull maintaining a place in the manager's plans.

If it will be a 4-3-3 with two eights, then it is difficult to see Turnbull fitting into Rodgers' vision for the characteristics of that role where he is usually looking for considerable energy and power.

Given O’Riley can play any of the three midfield roles, it would be surprising if Turnbull was to become a first-choice pick again. And at his age (23), that may not be the role he craves.