David Turnbull v Tom Rogic: Which should Celtic boss Ange Postecoglou choose? - James Dailey

Under the microscope on this occasion is what the potential positives and negatives of David Turnbull versus Tom Rogic might be should Ange Postecoglou decide to drop one from the starting line-up at some point.

Doing so would likely improve the overall defensive structure of the midfield, while also increasing creative options from the bench. The latter is something that has become an issue so far this season.

Let’s begin with an updated comparison of defensive and pressing metrics for the two players in league games so far this season, which I also shared last week:

That radar offers some context as to the relative value each player has been offering while defending and pressing, with Turnbull generally having offered more. Their relative performances in European games have been comparable.

Here is an expanded comparison to offer additional context, with Glen Kamara a good benchmark for a European level midfielder when it comes to defending and pressing:

This radar reflects various interesting nuances between how Celtic and Rangers defend and press.

For example, the average pressure distance metric shows how far from their respective goal-lines each player engages in a pressure action, on average. The disparity reflects the more aggressive nature of Celtic’s pressing system, which also manifests in the volume metrics like the number of counter-pressures.

Despite the higher level of aggression, we can also see that Kamara has offered higher possession-adjusted metrics, such as interceptions, and been far more effective defending against opposing dribblers and winning tackles.

This is a table assembled using a combination of available games StatsBomb covered for Celtic and Rangers across Champions League qualification, Europa League qualification, first group stage games, and the first six league games.

These raw metrics also show the degree of disparity in pressing, as Turnbull has averaged about a third more pressures per 90 minutes played versus Kamara. However, as the radar shows, the volume of defensive regains is similar. Counter-pressing metrics show more intensity as well, but with both Celtic players having a significantly higher failure rate.

READ MORE: Celtic manager Ange Postecoglou's problem isn't lack of Plan B but lack of depth to re-energise Plan A

When analysing all these metrics, it appears that Turnbull is offering more value and is more effective than Rogic in defending and pressing, but that neither are particularly well-suited for the requirements of Postecoglou’s high-press system. Rogic appears particularly worrisome in this regard.

Obviously, chance creation and goal scoring are also vital factors to consider. Last week's column reviewed the relative track record for shooting for Turnbull and Rogic. Here is an attacking radar with additional context for league games so far this season:

This also offers interesting information, as the deep progressions metric is indicative of Turnbull being more active in dropping to assist in build-up play, and being far more accurate when passing under pressure. Turnbull also has the edge in xG, though both are at high levels.

Where Rogic shines through has been in creating chances from open play for team-mates, as his 0.38 compares to Turnbull at just 0.05. Additionally, he’s created that on an average of 1.97 key passes, for an average chance quality of 0.19 xG for team-mates. That is almost quadruple Turnbull’s level. Rogic also has been dispossessed at a far lower rate.

Further complicating matters, Turnbull has offered a significant amount of chance creation for team-mates via set-piece deliveries, which significantly closes the overall gap with Rogic from open play.

Given the players within the squad available for selection, Rogic is likely a reasonable selection along with Turnbull for games at home versus bottom half of the table opposition, and select away games on bigger pitches such as Ross County.

However, for European group stage games, most away games domestically, and home games against top-half opponents, Rogic’s creativity is not enough to counter-balance his lack of defensive and pressing acumen - particularly when paired with Turnbull.

As witnessed versus AZ Alkmaar, attempts at relatively high-intensity pressing can create significant vulnerabilities in defensive transitions when the pressing is unsuccessful and inefficient.

While the composition of the midfield is not the only issue relative to the questions raised about Celtic’s press here, there has been enough sample size now to formulate my opinion, which is that Rogic, and not Turnbull, should be dropped if Ange decides to shift away from a Callum McGregor-Turnbull-Rogic midfield three.