Tuesday 16 May 2017

The Championship Playoff Defensive Kingpins.

The second leg of the Championship playoffs are played out over the next couple of days and while the headlines will inevitably be grabbed by the goalscorers I thought I'd spread a little love for the workhorses whose job it will be to prevent the net from bulging.

Analytics has unsurprisingly concentrated on attempting to quantify those involved in the actual act of scoring or not.

Expected goals, either from the perspective of the the player taking the chance, those who immediately set up the opportunity or the keeper trying to make the save, can begin to quantify the probabilistic based process between the singular outcome.

However, defensive actions are more problematical.

Mere counting actions, without context can lead to misleading if plausible conclusions.

My first ever blog gloriously demonstrated that the recently promoted Stoke City may have lead the league in fouls committed, but once possession and opportunity were factored in it was actually Arsenal that perhaps deserved the title of dirtiest team in the Premier league.

A simple tweak, that more reveals the importance of an individual to the defensive actions of his side is to look at the proportion of defensive actions a player has attempted compared to the proportion of playing time he has enjoyed.

These actions may range from attempted tackles to interceptions and clearances.

We can easily add a further layer of information to this gradual contextualisation of defensive stats by including the average position on the field from where each player carries out these actions, as well as how spread out these actions are from this average point on the field.

Here's the Defensive workload undertaken by the players who may lineup in this week's Championship playoff second legs.

A defensive quotient corrected for playing time of 1.0, suggests a player is participating in an average share of his side's defensive duties and the larger the average % distance his actions occur from his opponents goal, the more his mixing it in the muck and nettles of his own half.

So two predominately green bars denote lots of defensive actions, predominately in his own half. And red and red equates to a lightly defensively involved player, likely playing much higher up the field.

Great to see Deano still plying his deep lying defensive skills at a high level!

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