Rodgers' Celtic tactical tweaks that will bring European progression

While this information was not immediately available, it felt like it was a poser worth dedicating a piece to.

Defensive Summary

Firstly, let’s compare two very small samples across the two competitions regarding StatsBomb’s defensive metrics.

Quite a stark contrast and unexpected in many ways. Celtic are giving up 1.14 xG per game in the SPFL yet only 0.68 in the CL despite playing with nine men for a significant period.

The quality of opposition shot is double and not in the way you’d think – the average shot against in CL is only 0.06 while in Scotland it is 0.12.

Celtic are giving up more set piece xG, counter-attacking shots and more clear shots at home versus the CL.

Most surprising is the average defensive distance in the CL is 51.09 which is much higher than Ange Postecoglou had the defence and even further up the pitch than in Scotland where it is 46.83 – a couple of metres deeper than last season.

The only 'expected' number is perhaps the volume of shots being 12 in the CL and 9.75 in the SPFL.

Another telling piece of data is opposition passes completed per defensive action (PPDA). This is a proxy for pressing intensity.

READ MORE: The Rodgers Celtic factor that has helped Hatate 'come alive'

Celtic allow the opposition 15.06 passes on average before a defensive action in the CL whilst only 7.19 at home.

So, Why?

There are three elements to how Brendan Rodgers has tweaked Celtic’s out-of-possession shape in the CL.

1. At home Celtic do not generally lose the ball for sufficient periods of time to need to form any kind of stable defensive block. Usually, the opposition play a long ball up the park and the key is to be on the end of the second ball.

In the CL, and especially against sides like Maurizio Sarri’s Lazio, the opposition are capable of long bouts of possession. Celtic need to have a strategy for out-of-possession play.

Rodgers has Celtic set up in what can be called a mid-block. That is, holding a pattern of defensive alignment between their own defensive third of the pitch, and the middle third.

In this case it is usually a 4-4-2 shape with Reo Hatate joining Kyogo Furuhashi at the point.

2. The shape Celtic adopted is the same as under Postecoglou but with differences. 

Firstly, there is a more studied compactness to the team. The full-backs push on slightly less and the midfield, with Matt O’Riley closer to Callum McGregor, is more solid. 

O’Riley is crucial to this as his defensive strengths are ever-improving. Under Postecoglou he was the first presser with Kyogo, but under Rodgers, he values the Danes anticipation and decision-making prowess more centrally and deeper out of possession.

3. Finally, Celtic are pressing less but more intelligently than under the Australian.

The PPDA numbers show that starkly. That is not to say Celtic do not press aggressively when it is judged appropriate to do so (usually when the opposition are pinned back in their own final third.

But when the opposition have safe possession around halfway or beyond, it is more important for Rodgers to maintain a good, disciplined shape. The onus is then on the opponents to use sharp, crisp passing or one versus-one skill to find space.

Last season, technically capable sides could pass through Celtic’s press and counter with relative ease.

Here are two examples from the last couple of matches

On the right, against Lazio, Celtic are deeper and the full-backs markedly so. O’Riley is tucked back in with McGregor as is Hatate. 

READ MORE: Dalglish on why Celtic must continue knocking on Champions League door

On the left against Kilmarnock, this is not far away from the usual shape last season with the full-backs slightly inverted and pushed on to form a three in front of the back two. The two 8s then push on to support Kyogo. The forwards are clearly much higher on average.

And in some regards, it is working. Remember last season in the CL, Celtic conceded 1.72 xG per game, 13 shots a match and 0.13 xG per shot as well as 2.5 clear shots per game.

Performance / Outcome

Despite all of this, the outcome of the matches have seen Celtic concede four goals in two CL games (and save a penalty) while only letting in five in eight SPFL ties.

These discrepancies are why one studies performance over outcome. In the CL, Celtic had suffered from two (arguable on the second one) errors from Joe Hart: firstly, failing to get across to a long-range free kick in Rotterdam; secondly, failing to keep a header from a corner out at home to Lazio.

The Italians'  winner came when a rusty Cameron Carter-Vickers dallied on the ball in the 95th minute central to his own goal around 35 yards out and five Lazio players poured forward onto a disorganised defence. A superb cross was met by one of the most decorated players in world football to head home.

Three big errors have yielded three goals against. None of them (two headers and one free kick from distance) had high xG’s associated with them yet Celtic are sitting on no points and an average of two goals against per game.

 Seven big errors have been recorded leading to shots in Europe and this has yielded three goals off a total xG of 0.66.

In Scotland, 12 defensive errors have yield three goals but with a xG of 1.47. Simply, domestic forwards are less capable of exploiting the mistakes Celtic make than those in Europe.

Indeed, 66 shots have yielded 7.96 xG but only four against (not including the Kilmarnock game).

Summary

Rodgers has successfully tweaked Celtic’s out-of-possession defensive line to be higher, more compact, and more selectively aggressive in the press.

This has given Celtic remarkably good underlying defensive team performance metrics.

However, individual errors have undone all that good work and Celtic sit with no points and four against.

In Scotland, Celtic are giving up far more chances, but the opposition are less capable of taking those chances.

Nevertheless, much improvement is needed. Celtic need to be less open in the SPFL and to cut out individual errors in the CL.

Good news - they have a coach who can work these things out.