Bolingoli Assessed – Is Tierney Impossible to Follow?

With a Twitter handle renaming movement amongst the Celtic support, it is fair to say Bolingoli is becoming something of a cult figure for the Champions. Two solid performances in the crucial away matches in Stockholm and at Ibrox have seen the Belgian play his part in reaching group stage football, and topping the league.

Whilst replacing a £25m (undervalued) may seem an unfair benchmark, it nevertheless is Tierney to whom we must compare him now that over 900 minutes have been played.

Defending

I use two aggregated metrics to summarise defending capability – Defensive Action Success Rate (DASR%) and Possession Win% (note neither metric accounts for passing). Both are more useful for central defenders whose primary job is undoubtedly defending. Attacking full backs will have deflated numbers as they will often lose the ball in the attacking third. I can indicate this through Final 3^rd Possession Lost and a full back who never crosses the half way line will likely have better numbers than an attacking wing back.

That being said, I would argue Bolingoli and Tierney fulfil similar roles at Celtic. They are expected to get high and wide often and so make for a fair comparison.

Tierney is on top by both metrics. He wins 6.55 challenges per 90m compared to 4.98 by Bolingoli. Tierney is, however, dispossessed slightly more (2.62 to 2.35 per 90m).

Aerially, the taller Bolingoli is more effective. He wins 1.45 challenges per 90 compared to 0.9 by the Scot. He also loses less – 1.09 compared to 1.25.

Essentially, Tierney is the more effective tackler. But overall, from his defensive actions, he also wins possession by 2% more.

Outside of these metrics, it is Tierney who performs better all the way. A summary of other defensive actions below.

All values per 90m

Tierney blocks more crosses, misses less blocks, commits less fouls, loses the ball in his own defensive third less times, and clear his lines more often.

Tierney’s error rate has always been low – he takes very few risks defensively. Bolingoli is just above my personal threshold of 0.5 per 90m at 0.54.

Finally, Bolingoli is being packed slightly more often than Tierney was. Both players will often not be in the picture when attacks come down their side due to their attacking endeavours. But it is Bolingoli who is bypassed slightly more often.

The only defensive metric I have where Bolingoli comes out on top is that he wins the ball back in his own defensive third more often – 1.72 to 1.36 per 90m.

Otherwise, Tierney is clearly the stronger defender. But bear in mind it is a high bar.

Ball Progression

These covers passing, assisting and getting the ball forward on the run.

Both players are energetic and aggressive in their attacking.

I have only started to track Progressive Runs (carrying the ball more than 10 metres in the opponent’s half) this season Bolingoli completes 2.26 per 90m – the squad average is 2.9.

Tierney had a very good assist record at Celtic with 35 over his career. This worked out at 0.22 per 90. Bolingoli has 2 so far at 0.18 per 90m.

However, Tierney was operating just above his Expected Assist rate of 0.214 whilst Bolingoli is exceeding his 0.126. It is early days but we’d expected the Belgian’s to regress towards xA.

Tierney creates significantly more chances – 1.42 per 90m compared to 0.91 – this works out at 5 more chances over 10 matches. Tierney creates a chance every 37 passes whereas with Bolingoli is it 67.

The young Scot is also the stronger runner. He completes 1.35 dribbles per 90 that take out at least one opponent. The less speedy Belgian achieves 0.45. Indeed, Tierney attempts more “take-ons” with 0.91 failing compared to 0.72.

Where Bolingoli has the edge, however, is in his midfield passing. He is adept at getting the ball through the lines and completes 6.7 Pack passes per 90m. Tierney’s average was 5.5.

He is also ahead on Secondary Assists – the pass before that which leads to the shot. He creates 1.36 per 90m compared to 1.1.

Bolingoli, then, operates more effectively in the middle third. His overall Packing rate (accounting for passing dribbling and receiving forward passes) is an impressive 72 Impect score whilst Tierney’s is 63.

Attacking

Neither player is known for scoring with Bolingoli yet to get off the mark, and Tierney managing 8 in 170 appearances.

And Tierney takes nearly twice as many shots as Bolingoli (0.92 to 0.54 per 90m). His Expected Goal is slightly higher at 0.07 per 90m compared to 0.059.

Indeed, 36% of Tierney’s incursions into the final third result in some kind of positive outcome (shot or corner) but it is only 24% for Bolingoli.

Tierney plays more passes into the opposition Danger Zone (1 to 0.45) and has possession in the opposition box more frequently (2.05 to 1.18).

Where Bolingoli has the edge is that he wins the ball back more often in the final third – perhaps an indicator of more effective pressing ability (0.27 to 0.13).

Summary

Celtic’s conundrum as regards their development model is that they cannot replace a £25m plus player with another (at least he won’t be proven yet). It is clear Tierney is one of the most gifted players of his generation. To this observer (I don’t have the data) he will prove better than Andy Robertson.

Not posting as good performance numbers as Tierney then is not a slight on Bolingoli.

In fact, his defensive numbers are not too far from Tierney’s but there is no doubt the Scot is more effective in his own defensive third. Bolingoli needs to cut down on defensive errors.

Bolingoli is not as creative as Tierney in the final third, in fact the numbers suggest as much as half as effective.

But where he is more effective than Tierney is in midfield ball progression – i.e. in the middle third. Either by taking up good positions to receive the ball on the left, or by (often) inside passing to midfielders, Bolingoli is more effective in breaking opposition lines.

This is still early days and I am comparing 170 appearances with just under 10.

Bolingoli looks to be a decent attempt to replace a one in a generation talent.