Arsenal: Where does Kieran Tierney improve upon Sead Kolasinac?

Per Arsenal head coach Unai Emery, Kieran Tierney will be ready to play against Sheffield United. So where does the £25 million signing improve upon the man he will replace, Sead Kolasinac?

After signing for £25 million in the summer transfer window, this moment was inevitable. Kieran Tierney was always destined to be Arsenal’s starting left-back. That’s what they signed him to be. But after arriving needing rehab for a sports hernia operation, his start to life in north London was delayed somewhat.

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However, two months and eight Premier League games into the new season and the moment has finally come. Tierney is set to start a league fixture.

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Head coach Unai Emery was asked about the availability of the 22-year-old ahead of Monday night’s trip to Sheffield United. His answer left no doubt:

"“He’s ready to play. Now we have two options in that left-back role with Sead Kolasinac and him. We’re going to play a lot of matches after Monday. We will need every player. It depends how he comes into the first training with us, Sead, after his international matches. We now have two players in that position and we can use one on Monday, it depends how they are, one or the other.”"

There is a sense of excitement for Tierney’s long-awaited league debut. He is, after all, seen as a crucial piece of the next era of the team. But what will he actually offer that incumbent starter Sead Kolasinac cannot? Where will Tierney improve on a player who, while a little suscpetible defensively, is an entirely solid Premier League full-back? Well, there are two key areas, and neither of them defensively, oddly enough — Tierney is a better defender than Kolasinac, but his work without the ball is not the crucial difference between these players.

As modern football has evolved and the introductions of the high press and possession have swept throughout the game, the role of the full-back has changed also. Rather than remain compact and close to the nearby centre-half and lump passes up the channel to the winger, a full-back must provide far more to the team, especially on the ball.

Two crucial areas are escaping the high press and chance creation from wide areas. Tierney excels in both of these. Kolasinac, on the other hand, does not. The following statistics do not paint the entire picture, no statistic ever could. But they do help to provide some insight into Kolasinac’s struggles, and Tierney’s excellence.

Kolasinac’s pass completion rate is 86.8% this Premier League. That may seem like a good figure, but it is the highest of his time at Arsenal. In the other two seasons, he was at 80.1% and 77.7%. He is at a similar rate in the Europa League as well. Tierney, in contrast, completed 92.9% of his passes in his lone Europa League match this season — don’t take this number too seriously as it is one game.

Moreover, Kolasinac’s dribbling and ball retention are also very poor. This season, he has had 0.6 unsuccessful touches per 90 minutes and been dispossessed 0.2 times per 90 minutes. Last year, it was at 1.5 unsuccessful touches per 90 minutes and was dispossessed 0.8 times per 90 minutes. He also completed just under half of his dribbles. Poor passing, poor dribbling and inconsistent touches make breaking out of the high press extremely difficult.

Meanwhile, Kolasinac’s crossing has been extremely wayward also. Last year, he attempted just 3.25 crosses per 90 minutes. Of those, only 0.5 per 90 minutes were accurate. Tierney attempted 5.48 crosses per 90 minutes in the SPFL last season, has displayed terrific delivery from out wide with one assist and four chances created in his lone Europa League appearance.

So, all in all, Kolasinac’s passing is inaccurate, his dribbling and control poor, and crossing wayward. For a full-back, that is problematic. And Tierney excels in all of these areas. This is where the greatest improvement will come from the impending left-back swap.