A word about Celtic defender Alexandro Bernabei...

Not only was the transfer fee for a young player (£3.75million) high in the context of Celtic and Scottish football, it represented a new market for the Champions to explore. This was, perhaps, more 'City Group database' than historical managerial knowledge.

Since joining, the 22-year-old has experienced the joy of the birth of his first child in a new continent while also trying to dislodge the ever-improving Greg Taylor from the left-back berth.

A flurry of appearances in November and December 2022 was followed by a lack of squad places in January and February (one bench place in seven matches) before a full runout recently against Hearts at Parkhead.

That appearance took the defender over the 900-minute threshold whereby meaningful data is available to assess what it is the Hoops have on their hands.

Let’s dive in then and look at him using several recent full-backs to benchmark his progress.

The chart contents do vary and this is due to data availability by season. Also, in this article, you will get the bonus of Alistair Johnston’s data for comparative purposes, as he has similarly passed the magic 900 number.

Bernabei vs Taylor

Bernabei is in direct competition with Taylor for a starting spot at left-back. Let’s first compare the two using StatsBomb data:

Remember, with StatsBomb data, they are comparing the players to all other individuals in the SPFL in that position. As Celtic are so dominant, it can seem as if players from the Parkhead side are always world-beaters relative to members of the Ross County squad (for example). 

So where Bernabei and Taylor are in the 99th percentile for xG build-up, that is relative to the rest of the full-backs in the league. 

READ MORE: Kevin McKenna on Celtic: Joe Hart deserves more appreciation

What is interesting, and we will dive in deeper below, is that Bernabei is stronger in tacking, intercepting, pressurising, dribbling and aerially.

Taylor is stronger in being more resistant to being dribbled past and in conceding fewer fouls. He also has slightly better pass completion stats. Based on this, you might be picking Bernabei.

StatsBomb's proprietary On-ball Value (OBV) metrics are:

It's a remarkably similar view – the StatsBomb model prefers Bernabei’s passing but Taylor’s dribbling and carrying with the Scot having the slightly higher overall OBV.

Let’s try to unpack this a little further...

Defending

This framework is normally used for central defenders and has a long history of matching the eye test well. A caution for Celtic full-backs: as they attack a lot, many of the defensive actions captured actually occur as attacking actions in the opposition half. However, they are aggregated over a season’s data so the same limitation equally applies to each player.

It could be argued that what meets the eye test is the fact that Johnston and Mikael Lustig stand out as highly competent defenders compared to the recent pool of Celtic full-backs. 

As a counterpoint, Jeremie Frimpong is by a distance in the bottom left. In effect, he was a winger nominally placed at full-back tasked with getting the ball quickly up the park. That minimal set of skills was enough for a huge transfer fee from Bayer Leverkusen and will likely see him progress to greater things.

Bernabei trends at the bottom of the 'middle class' of recent Celtic full-backs’ defensive performances. Defensively, he is behind Taylor and Josip Juranovic of current times. What is driving that?

The above plots, for this season’s full-backs only, show the average number of times per 90 minutes they either recover the ball or lose the ball resulting in opponents (recoveries) or team-mates (turnovers) being out of the game due to a defensive action.

Note that because Celtic are so possession-dominant their players will tend to turn over the ball more than recover it.

However, of the current full-backs, Anthony Ralston manages to maintain an equilibrium of such events. 

All others tend to lose it more than recover it, with Bernabei being the most likely to do both. However, the differential between recoveries and turnovers (-1.79) is by far the highest.

This propensity to turn the ball over either from loose passes or getting caught in possession is driving the incredibly high personal error rate allied to the number of times he loses the ball in his own defensive third of the field.

The Argentine is a real outlier in this view. Whereas Johnston is incredibly safe in his defending - with virtually no errors and very low possession lost in the defensive third - Bernabei is the exact opposite and makes Boli Bolingoli look like Paolo Maldini in comparison.

One explanation for this (outside of the obvious one of poor decision-making) is the level of defensive aggression. StatsBomb data highlights this using the number of pressures applied per 90 minutes and the number of ball regains made in the defensive third.

Bernabei clearly defends very aggressively with only Diego Laxalt applying more pressures. Bernabei can regain the ball but, as we have seen above, that can come at a cost when those aggressive actions go wrong or are mistimed. 

Defensively, then, Bernabei matches the profile of a Postecoglou full-back in his pressing ability and aggressive intent but clearly there are major learnings needed in terms of when to be aggressive and when to be more circumspect.

Ball progression

Celtic need their full-backs to progress the ball up the park. In this context, it is worth considering the simple act of running with the ball (ball carries) and receiving forward passes that take opponents out of the game (pack receives).

Bernabei is the closest in recent times to Frimpong’s elite-level ball-carrying ability. He seems to have a low centre of gravity, a muscular frame and great balance. His ground speed is also good, meaning he can carry the ball quickly and effectively. As we have seen with Frimpong, this is a sought-after commodity in the modern game where defensive structures are highly organised; a player running at pace disrupts opposition shape.

He needs to improve his ability to get into space and receive forward passes. He lags slightly behind Taylor and Johnston in this regard, but not by much. Some of this is down to learning the positioning required for the inverted full-back role. This is complex and takes time, as we have seen with Taylor and Ralston.

The other side of ball progression is the ability to make passes forward through the opposition. Pack passing is the metric used to measure this skill.

This is also a view that highlights team tactics versus individual skills. All the top five players in the chart are recent full-backs. This tells us that looking for such forward passes is tactical instruction. 

We know Brendan Rodgers' team would recycle possession rather than risk losing the ball with a dangerous forward pass. Neil Lennon’s teams would tend to get the ball forward more quickly and directly even if that meant losing possession. 

Postecoglou has, it could be argued, a fantastic blend of control versus passing aggression and these numbers support that. 

But even allowing for debates on system v player, it is clear that Johnston is exceptional in this regard as his average pack score is way ahead of his peers.

Bernabei’s is better than both right-backs but slightly behind his direct competitor, Taylor. Overall, the Argentine looks very much like the ideal Postecoglou full-back as regards ball progression.

Chance creation

Celtic's full-backs are fully involved in attacking patterns. Many clubs instruct their wide defenders to stop at the halfway line. At the Parkhead club, there is a need to supplement the attack and interchange with the wide attackers.

Getting balls into the opposition box is assessed by the number of passes into the central danger zone and overall cross-success percentage.

Juranovic was particularly strong here, as was the much-maligned Jonjoe Kenny. Bernabei is doing a good job getting balls into the danger zone but needs a lot of attempts to do so. No one in this peer group attempts more crosses (4.48), but only seven per cent are successful, with just Jeremy Toljan being less accurate.

Let’s consider the chances this helps to create:

Bernabei is doing quite well here, as measured by the number of chances he creates for others (passes leading to shots) and the quality of those chances (expected assists or xA). 

He creates the same number of chances as Taylor but of a slightly higher quality. Indeed, only Frimpong (2020-21) and Kieran Tierney (2017-18) created more.

It is more a question of improving quality with Bernabei, which echoes his defensive performances. More care, attention and precision are allied to better decision-making. But the raw materials are clearly evident.

Attacking threat

Synthesising StatsBomb's xG build-up with my own aggregated attacking threat metric gives us an overall view of contribution to the team's attacking threat:

Again, we see a healthy contribution in the number of attacking moments (attacking threats per 90 minutes) but the quality of those contributions (xG build-up) are lower than Ralston's.

Taylor’s contributions to attacks tend to result in a higher xG than Bernabei’s but, with the Argentine, you get more overall.

Summary

Bernabei is a fascinating mix of loads of things – he is heavily involved and has a high volume of both defensive and attacking actions with mixed quality.

Most concerning is his tendency to lose the ball in dangerous areas of the pitch resulting in counter-attacking opportunities for the opponent. He turns it over too often and in bad positions.

Yet he is probably the most aggressive full-back Celtic have – a full-back equivalent of Carl Starfelt perhaps. He has the tools to be a modern player in that position.

There are many encouraging signs about his ball progression and attacking threat capabilities. He can carry the ball forwards at pace and his forward passing is effective. As with his defensive output, more care is needed sometimes to ensure higher-quality outcomes.

Celtic have had success recently with Reo Hatate, taking a young player with all the tools in the box and refining them gradually over time to become more effective. Both Bernabei and new striker Oh Hyeon-gyu look similar in that regard.

Postecoglou can be trusted to hone the best out of Bernabei - but fans may need to be patient.