Measuring Defensive Improvement

The desire is to see continual improvement but how measure it?

Using the defensive metrics Defensive Action Success Rate % (DASR%) and Possession Win % and comparing last season to this, we can see how the defenders have improved against those key measures.

The analysis is restricted to those who played over 900 minutes AND were present in both 2017/18 and 2018/19. So, no Toljan or Benkovic, for example.

The most virtuous position is top right. This is where you see players who have improved in both metrics since last season.

Sadly for Celtic, the biggest improver was Boyata who has just left the building for £0. He improved his DASR% by 4% and his Possession Win% by 7%.

The better news is the step forward Simunovic has taken with DASR% up 2% and Possession Win % up 6%.

I have included Brown in this analysis as his role is primarily a defensive one.

We can see that both the experienced players Brown and Lustig had very similar numbers from last year – not improving but consistent into their mid-30s.

Ajer is on the wrong side of the graph but his numbers are very similar to last season over many more minutes (2911 up to 3473). His DASR% is down 2% but Possession Win % is up 2%. A season of consolidation for him. And in fact, Boyata’s improvement at 28 illustrates a not untypical development cycle for a centre back. Ajer is only 21.

The sad story is of course Tierney who has struggled with hip problems all season. Now recovering from surgery, his DASR% is down only 1% but Possession Win% down 10%. Share widely and I am sure this will put Arsenal off!

Jullien needs to be talented to match the efforts of Boyata and Benkovic. And Celtic likely needs at least one more centre back.

I think this is a powerful view. Simple, yes, but these defensive metrics match the eye test in my experience.

I want to see Ajer push on and Simunovic continue his improvement. Lustig is a big miss defensively. And a priority is to get Tierney rehabilitated and on the development path again.