The Celtic comparison that lays bare Ange Postecoglou's coaching excellence

To start a review of the 2021-22 season, it is useful to try to place it in some historic context. The 2019-20 campaign was one of Celtic’s more dominant recent domestic terms.

Yes, the 2016-17 Invincible season was obviously a historic one, but its underlying performance metrics actually lagged the 2019-20 campaign.

The two losses in the pandemic-shortened season included the defeat at Livingston after an early Ryan Christie red card and a festive period loss to Rangers, who were a far stronger opponent compared to their newly-promoted vintage of 2016-17 and had around triple the wage bill.

Let us start on the front foot: attack.

This radar shows the relative dominance of both sides, with this season’s vintage edging xG differential 1.75 versus 1.55. Postecoglou’s side had more possession, passed and crossed into the box more and played short balls ball out via the keeper much more, while the 2019-2020 side was modestly stingier in limiting opponents’ chances.

Now, defending:

This radar indicates the two teams were pretty comparable from a defensive perspective, though Postecoglou’s side played a higher average line and was more advanced up the pitch in pressing and counter-pressing. The 2019-20 side was a bit more restrictive in limiting opposition entries into creative passes (deep completions) around the Celtic box.

Next up, shots:

This radar once again shows many similarities, but a couple of metrics stand out. Despite Postecoglou's team playing higher and pressing more further up the pitch, clear and counter-attacking shots were conceded at a lower rate than the 2019-20 side. In addition, despite some challenges they faced playing out from the back at times this season, high-press shots conceded were actually a good bit lower than the 2019-20 side.

Finally, on-ball value:

What stands out with this radar helps to explain why the 2019-20 side were able to, as shown in the first radar in this column, score 2.97 goals per game compared to 2.00 in xG.

If we adjust each team’s goals per game to back out penalties scored, which is more of a direct apples-to-apples comparison versus the 2.00 and 2.28 xG figures, they drop to 2.80 for 2019-20 and 2.29 for this season.

As reflected in the shot and goalkeeper OBV metrics directly above, the 2019-20 side finished marginally better but faced particularly poor opposition keeper play.

In fact, for that entire season, the side had 65.90 in post-shot xG versus 82 goals scored from shots on target (does not include own goals or penalties). Those metrics for this past season were 85.22 and 86.

In summary, this season's vintage was more organized and better coached. The playing style and system installed appear to have been robust, as metrics that take in aspects such as average chance quality were significantly higher while they also measured better at limiting things like oppositions’ clear and counter-attacking shots. There is an argument the 2019-20 squad was a more talented one but that they were utilised in a less coherent and effective fashion. 

In the next update, this comparison will continue by drilling into how the respective players from each team performed. 

Overall, the most exciting element to these sorts of analytical exercises is the ways in which it suggests the potential for further performance advancements as Postecoglou's squad is upgraded with players who possess better-fitting skillsets for his playing style.