How well is Celtic's Greg Taylor actually performing?

Nowhere is that felt more in the Celtic line-up than at left-back. Kieran Tierney had everything a supporter could wish for – a local boy, a passionate supporter with an all-action, swashbuckling style and bags of genuine talent. He’d play for free, you would imagine.

There is no doubt Tierney will prove to be one the foremost Scottish players of this generation and there are signs he is already outgrowing Arsenal. A move to a world superpower, Real Madrid, has been mooted.

Replacing him at Celtic has been a challenge. Boli Bolingoli was an ill-fated signing for many reasons and has now been frozen out of the first team. Diego Laxalt, a Uruguayan international, came in from AC Milan. He proved completely ill-suited to the team's style of play.

Amid all that Greg Taylor, a promising youngster signed from Kilmarnock, has been working away trying to make the left-back slot his own.

As the final four matches of the season approach, it seems he has achieved that... but does Taylor deserve to be considered Celtic’s first-choice number three afterwards?

SPFL comparisons

Using StatsBomb data, we can compare Taylor specifically with rival left-back Borna Barisic and with the wider population of full-backs:

Barisic is stronger in the tackle, lets fewer players dribble past him and turns the ball over less often. Taylor is the better passer, general ball progressor, is surprisingly stronger in the air and applies more pressure on the opposition.

Quite different styles of players then, with different strengths and weaknesses.

Both score highly in the percentiles compared to their SPFL peers. This is not surprising as Celtic and Rangers are very dominant. Their percentile rankings tell you more about the dominance of the teams they play for than their individual characteristics or their relative strengths versus, for instance, a Tierney.

Celtic left-backs comparison

Comparing Celtic players to other Celtic players is arguably a better benchmark than comparing them to the likes of Hibernian or Ross County players.

Let’s compare Taylor to the recent cadre of left-backs. Where the data allows, the players included will be Tierney, Laxalt, Bolingoli and Liam Scales.

Defensive Action Success Rate aggregates all defensive actions and assesses whether they were won or not. Possession Won from Defensive Actions reports those actions that resulted in Celtic winning possession.

Tierney is, first and foremost, a very accomplished defender. While he may be remembered as a rampaging attacking full-back by many, he had a highly uncomplicated and therefore effective approach to defending: low risk and safety-first.

Scales’ aerial dominance accounts for his ability to win the ball back, especially in the air. But Taylor, despite being decent in the air, is closer to the ill-fitting Bolingoli and Laxalt in overall defensive performances.

We perhaps cannot expect any incumbent to be up to Tierney’s standard (he did cost Arsenal £25m after all) but so far, at least, Celtic have not found a left-back to rival the Scotsman’s defensive prowess.

READ MORE: What Celtic's performance against European teams and Rangers tells us about 'Angeball'

TCW columnist Ross Goodwin provided a piece earlier in the week on prospective signing Mohanad Jeahze. What is noticeable about this player is his athleticism and recovery speed. Those are both aspects that are not Taylor’s strengths.

If we look at the number of times the players are taken out of the game by forward passes, we get a sense of recovery speed and positioning:

Again, Tierney comes out best here with the lowest rate of pack passes taking him out of the game. There is perhaps some perception bias against Taylor as, despite what he is often criticised for, he is solidly in the middle of this pack.

You can see that Laxalt was by far the player taken out of the game most often by opposition forward passes. This contributed to a toxic combination of Shane Duffy trying to plug gaps at left-back (not a strength) and Scott Brown trying to cover a lot of space in defensive midfield (and displaying natural age regression). Hence, last season the defence was a car crash.

Taylor is an improvement on “incoherent mess”. Faint praise indeed.

Tierney is, unfortunately, missing from the ball progression comparison due to the data not being available when he was around.

This is a shame as the suspicion is he would have been the only one who was competent in both carrying the ball at feet and progressing the ball through forward passing. Since he left, it has been a case of one or the other.

Laxalt was the happiest to bring the ball out at feet while Taylor is the most accomplished forward pack passer yet has a relatively low ball-carrying capacity.

On the other side of that equation is the ability to get the ball forward by being open to forward passes. Essentially, we can measure movement, ability to find space and ball control by looking at the number of pack passes received and the number of touches in the opposition box under the most pressure.

This chart emphasises that team style can influence. Tierney has the most touches in the opposition box but was quite low in the number of passes received. Under Ange Postecoglou, there is a greater propensity to play aggressive vertical passes to get through the opposition lines. Under Brendan Rodgers, the ploy was to probe patiently and await openings.

Nevertheless, Taylor has proven very adept at getting on the end of forward passes. The inverted full-back role is of course a different one from that of Tierney’s more orthodox wing-back role. Taylor pops up in central areas to receive the ball far more frequently.

Yet the life of a Celtic full-back is often an attacking one. Let’s look at expected assists and chances created – chance quality and quantity.

Tierney’s xA rate (over 0.2) would be the envy of many a midfielder and none of the recent crop quite achieve that benchmark. It is somewhat of a surprise that Bolingoli and Taylor are equal.

This again emphasises the difficulty Celtic will have to match Tierney’s levels of output. Nevertheless, Taylor is getting close.

Summary

It is not controversial to state Tierney is a very hard act to follow.

Taylor continues to adapt his game to the demands of Postecoglou and - especially in the realm of ball progression - is proving highly effective. However, he is not as defensive sounds as Tierney, nor able to display quite the same degree of cutting edge creatively.

Two, possibly conflicting, thoughts remain:

1) At 24 years old, Taylor is a relatively young defender who displays a thirst for personal development and adapts to the demands of his manager. In particular, the complex role of inverted full-back has been taken to with some success. He is especially useful in getting Celtic up the pitch.

2) Taylor fundamentally lacks some of the physical characteristics of athleticism and raw pace to assist Celtic at the highest (European) level. They will remain vulnerable to fast counters down his side and diagonal aerial switches.

SPFL sides target Celtic’s left-hand side of defence for a reason (well, two reasons to be accurate). As admirable as Taylor has performed, he is perceived as being on the weak side of that defence.

He remains a valuable squad player with a wonderful attitude - but Celtic should be looking for a higher quality first choice if European progression is the ambition.