Defining the Defence Grading Levels

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tl;dr

• Defence can be graded on a six-point scale in DataVolley

• We can attach any meaning to these grades, so I explore the best way to grade the defence to get the optimal defence analysis out of it

• I have simply adopted the grading levels of the pass for the dig. I use extended code to record spike cover digs, digs after block touch, and free ball-overpass digs.

Defence Grading Levels

Defence is usually measured by whether the defending attempt was kept in play (known as a dig) or not, i.e. the opposition killed the ball (known as a missed dig or dig error).  This is enough to measure a Dig % [Dig % = Digs/ Total Digging Attempts].  This performance indicator is the third most critical performance indicator correlated to success in volleyball (see link).  This is probably enough for most teams but if we want to improve the level of defence analysis (and in my case, improve my scouting skills), we need to fully grade the defence performance.   

In DataVolley, the defence can be graded on a six-point scale.  The grading levels are best (#), good (+), medium (!), poor (-), worse (/), and worst (=).  So what do these grades actually mean?  Well, DataVolley has its own definitions.  However, is it the best way to analyse the defence?  Remember, we can attach any definitions to the grading levels, as long as we are consistent within ourselves.  So, how should we define these defence grading levels to get the optimal defence analysis?  

Grading Other Technical Skills

This is one in a series on how I grade the various technical skills. Click on the links below to read more.

Pass and ServeDefenceBlockSettingAttack

My Current Definitions

How I currently grade the defence can be seen below.  Although I have four defence grades, I essentially code all digs as either in-play digs (D+, default grade) or missed digs (D=).  For Team SideOut Polonia London in the 2022/23 season, 89% of all dig attempts were coded this way.  I do code over-digs (D/) when it happens but it’s rare (4% of all dig attempts).  I do code poor digs (D-) when I can but I am not consistent with it (I coded 7% of all dig attempts this way).  Since I am not consistent with coding poor digs, I only measure dig performance as a Dig In-Play %.  This is fine for the most part but I can’t do any deeper level of defence analysis because I don’t fully grade the defence performance.  

DataVolley’s Definitions

How DataVolley grades the digs can be seen below (taken from the DataVolley 4 Handbook, page 42).  This is actually very similar to how I currently code defence except I code digs that create an attack situation as D+ (the default code) rather than D#. 

There are a few weaknesses to coding defence this way.  The first weakness is the D+ and D! grades are not utilised so we are limiting the level of defence analysis we can do.  The second weakness is that the over-dig (D/) doesn’t happen too often.  I mentioned earlier that over-digs only occurred 4% of the time for Team SideOut Polonia London in the 2022/23 season (84 times out of 2178 total dig attempts).  So surely we can get more use out of that grade.  A third weakness is the definition of a dig creating an attack situation (D#) and a dig that does not allow to build an attack (D=) can be quite vague.  What about those digs that land on the baseline but a player has time to comfortably bump set to one of the wing players?  Is that a D# or D-?  The fourth weakness is that the dig that creates an attack situation (D#) is quite broad.  It includes perfect digs where the middle is available to hit a quick attack and digs where it lands in the middle-middle of the court (zone 8 for those who know).  Both types of situations are not the same in terms of rally win rate.  You would expect the perfect dig to have a much higher rally win rate compared to a mid-court dig.  If you include digs that land on the baseline that a player can comfortably bump set to a wing player as a D#, then I’m sure the rally win rate will be distinctly lower than digs that land mid-court and much lower compared to those perfect digs.  They are all graded the same way but they are quite different in terms of rally win rate.  You want to be able to differentiate them in your defence analysis.      

Copy and Paste the Passing Grading Levels

Another way is to grade the defence to how you grade the reception, like in the diagram below.  One huge advantage is that I already know the reception grading levels so I can just do the same for defence.  Learning to grade and code the defence would be really quick.  It would also be easy for players to understand too, assuming they know how the reception is rated.  

One thing I don’t like about this is that it is probably extremely hard to dig a perfect ball, especially in transition, where players can be anywhere.  Another issue is what Joe Trinsey found (he’s the former USA Women’s Scout).  He found that with almost no exception, the players with the highest Dig % also had the highest dig quality/ average.  He found there weren’t many situations where there were players who dig lots of balls but not as accurately or players that don’t dig as many balls but can dig in-system.  So it means there’s no need to do the extra work to calculate a Dig Average because the Dig % does the same job.  One thing I don’t like about this is that it is probably extremely hard to dig a perfect ball, especially in transition, where players can be anywhere.  Another issue is what Joe Trinsey found (he’s the former USA Women’s Scout).  He found that with almost no exception, the players with the highest Dig % also had the highest dig quality/ average.  He found there weren’t many situations where there were players who dig lots of balls but not as accurately or players that don’t dig as many balls but can dig in-system.  So it means there’s no need to do the extra work to calculate a Dig Average because the Dig % does the same job.  

Grade Defence According to Attacking Situation

Joe Trinsey grades the dig as below (also see link).  He sees better value in knowing the transition hitting % under those situations.  One thing I like about grading defence this way is that it’s not about the “quality” of the dig but the situation it creates.  I assume that whether the setter/ non-setters set and whether it is a hand-set or bump set, both affect the team’s rally win rate.  

One thing I don’t like about it is what happens if the dig is in-system (D#) but a middle player gets in the way and sets the ball (D!).  It punishes the digger because the middle player got in the way.  Also, the setter will never be able to dig an in-system ball (D#) so they can never achieve a high dig quality average.  Having said that, Joe Trinsey did say that it is about transition hitting in those situations rather than dig quality.  Dig (In-Play) % may still be best for individual players and the defence grading average is better as a team.  

How Other Pro Scouts Do It

So I had a look, via DataVolley (.dvw) files, to see how the pro scouts from pro teams do it.  I acquired them when I swapped with the pro teams so we could scout them, e.g. when IBB Polonia London scouted Itas Trentino in the CEV Champions League.  I saw that the way the pro scouts grade the defence is essentially how DataVolley defines it (see below).  Some scouts may use D+ rather than D# for digs that create an attack situation, like how I do it.  

One surprising thing I found was that most pro scouts used D! for spike cover.  I am not sure how this became the standard way to code for spike cover.  I tried to code spike cover digs One surprising thing I found was that most pro scouts used D! for spike cover.  I am not sure how this became the standard way to code for spike cover.  I tried to code spike cover digs by opening up the Extended Codes window (I use the “W” button) and then pressing the “C” button for the Spike Cover option.  However, wby opening up the Extended Codes window (I use the “W” button) and then pressing the “C” button for the Spike Cover option.  However, when I tried doing this during the Small Countries Association Men’s Championships (see hen I tried doing this during the Small Countries Association Men’s Championships (see link), it was nearly impossible as rebounded blocks are the quickest part of the rally and you have no time to type two buttons.  ), it was nearly impossible as rebounded blocks are the quickest part of the rally and you have no time to type two buttons.  

So I really like the idea of using D! to mean spike cover digs.  I should be able to code “!” quickly.  I also don’t need to grade the spike cover digs since they are really reactionary digs.  We just need to know whether it was kept in play or an error.  So I really like the idea of using D! to mean spike cover digs.  I should be able to code “!” quickly.  I also don’t need to grade the spike cover digs since they are really reactionary digs.  We just need to know whether it was kept in play or an error.  

Defining My Own Defence Grades

Using the research above, I think the way I will grade the defence can be seen below:

The plan is to grade the dig on a five-point scale.  It is essentially how I grade the pass (see link) except I combined the perfect pass (R#) and positive pass (R+) together as D# and the medium pass (R!) is bumped up to D+.  The other change is that digs that do not allow to build an attack (i.e. shank digs that players have to chase down) are coded the same as over-digs (D/).  This will reflect how I define it for passing (R/).  I will use the spare grading level (D!) to mean spike cover digs, like how the pros do it.  This should make it easier for me to code spike cover digs in real-time.  I will use the spare grading level (D!) to mean spike cover digs, like how the pros do it.  This should make it easier for me to code spike cover digs in real-time.  

Implementing in Practice

When the new season starts, I will implement the above.  However, I will see what it is like in practice and make changes if necessary (I did have an idea of maybe combining both playable digs as one code and using the spare code to mean free ball digs).  

*** Update 3 June 2024 ***

I now grade the defence like how I grade the pass.  The main reason was it was so hard to rewire my brain to say a positive dig is coded as D# and a medium dig is coded as D+.  It was easier to grade the defence like the pass.  I use DataVolley’s extended codes to code Spike Cover Digs (DC) in addition to Dig After Block (DB) and Free Ball Dig (DE).  This has the advantage I can (potentially) grade Spike Cover Digs as well as Digs After Block and Free Ball Digs.  Click on this link to read more.