The right back review was a delicious stew of contradiction and intrigue, or as they probably still say in Somerset, a bugger’s muddle. Replacing Lustig isn’t easy you know.
Today I turn to the opposite flank and arguably the more onerous task of replacing Tierney.
It is another position where continuity has been hampered by injury but less so in that Bolingoli has appeared in 25.54 games worth of minutes, Hayes 8 and Taylor 4.42.
Hayes’ data is “polluted” with appearances in other position. Filtering for just his left back minutes is not possible I am afraid. Fair warning.
Defensive Performance
I plot Defensive Action Success Rate% and Possession Won from Defensive Actions % to get a composite overview of defensive performance.

The scale is deliberately a bit odd as it is the same scale I used for the right backs to allow comparison. Summary: the left backs are not as strong defensively. Sad face.
And I have plotted 18/19 Tierney for comparisons. This wasn’t peak Tierney as he was badly impacted physically.
But on core defensive performance, Taylor (small data sample alert folks) is the outstanding option.
Hayes does pretty well by this as well. But Bolignoli is no better than Tierney defending, and Tierney rarely needed to defend in Scotland. Neither does Bolingoli to be fair and we will get to creative output later. But you can see where I am going with this.
All three players are unsuccessful with just over 5 challenges / intercepts per 90m. Taylor wins 7.91, Hayes 6.63 and Bolingoli 5.68.
Let’s consider Defensive Errors and Defensive Saves.

Both Bolingoli (0.63 per 90m) and Hayes (0.88 per 90m) breach my code whereby no defender should have more than 0.5 defensive errors per 90m So red flags right there.
Taylor is, so far, on a healthy 0.23 and he leads the way on 0.23 defensive saves per 90m as well.
Defensive 3rd Wins and Recoveries node to positioning and anticipation to snuff out danger by regaining possession in your own defensive third.

Again, consistent scale to the right backs. Not a lot to choose between them here but Hayes again is a bit of a ball magnet concerning Recoveries. Which is a back handed way of saying he is in the right place at the right time to regain possession.
To summarise the defensive side of left back play I’d say small sample Taylor looks quite promising based on this data. Hayes is surprisingly robust as a defender but his error rate is well beyond my comfort zone.
Bolingoli is as effective as Tierney was in some respects but Tierney made very few errors.
Ball Progression

This may be a case where Hayes winger data is skewing things slightly but credit to him, he tops the three for progressing the ball through dribbling and passing.
Again, Bolingoli and Taylor are not too far apart. I am slightly surprised at this as Bolingoli does like the extravagant inside pass whilst Taylor appears quite a conservative passer. That’s why I’m here!
If we look at Total Impect – ability to Pass, Dribble and Receive forward passes, then Taylor has an unsustainable 101.54, Hayes a very worthy 84.75 and Bolingoli a very respectable 76.81. What this indicates is all three are playing high and wide and receiving a lot of passes from Brown and the centre backs.
For context, the traditional Pack King Ntcham is on 83.88. As I said, I doubt Taylor’s numbers are sustainable.
Creativity
Let’s start with the bread and butter – Expected Assists (xA) per 90m:

I’ve added Tierney 18/19 hampered model back in as this was his thing as an attacking full back.
Taylor is once again tearing it up within his small sample (don’t forget).
Bolingoli is not reaching hampered Tierney numbers in what has been an increasingly dominant Celtic side. Said it.
Hayes xA numbers are a wee bit disappointing. However, he does provide the most successful crosses (0.63 per 90m) and the most passes into the Danger Zone (1.25, Taylor 1.13 and Bolingoli 0.47).
Hayes is furthermore the most wasteful in the final third losing it 5.75 times per 90m compared to taylor (5.43) and Bolingoli (4.54). He also misses with 5 crosses per 90m, more than Bolingoli 3.21 and Taylor 2.26.
Conclusion
As with the right back berth, there is scant evidence Celtic have strengthened the team in this position. Bolingoli is the incumbent but is not matching Tierney defensive or creatively on last season. And that was stagnating, injured Tierney.
Hayes has manfully filled the void but is too error prone in defence and too wasteful in attack to be a long-term option.
We have seen very little of Taylor but in 4.42 matches of data the numbers suggest he should get a run.