With a little extra time on my hands I have taken started to look at what might be the differences and similarities between leagues, and with it whether there are any structural ‘rules’ in volleyball. Thanks to Michael Mattes and Manlio Puxeddu, who collected the files and Ben Raymond, who wrote the apps that let me crunch the numbers for the whole leagues. The leagues I will focus on are France, Germany, Italy, Poland, and Russia. For these leagues, I have almost full data for the 2016-17 season and I also think these are probably the top 5 leagues right now.
The libero was introduced into volleyball in 1998. Ostensibly, the reason was to balance the effectiveness of the attacking and defensive phases of the game by improving the quality of the defence. I have written that the libero did in fact change the game, but perhaps not exactly how we imagined it would. Now we have the chance to actually test the proposition.
In the previous post in this series on the break point phase, I made the observation that the break point percentage was lower in the rotations in which the middle blocker was serving and therefore the libero was NOT on the court. I wondered if this result could be caused by the fact that the middle blocker typically float serves (which we also discovered reduces break point rates) or that the middle blocker is a worse defender than the libero, or of course both.
In my previous post, I introduced the concept of ‘attacks per defensive opportunity’ (ATT/D) as a measure of a team’s defence. I have used that measure here to investigate whether or not the libero does actually have a meaningful impact on defence.
In the first case we looked at the rotations with the libero (P1, P6, P4, P3) and without the libero (P5, P2). Here we can clearly see that teams in every league created ‘significantly’ less attack opportunities without the libero compared to when the libero was on the court. It is not clear from this however the effect of the service type.
If we look at only the jump serves, we still see the same relationship (with the exception of Poland). The defence is better with the libero than without. The total line and jump serve lines are very close together indicating that very few middle blockers jump serve. We can extrapolate from that information that perhaps middle blockers in Poland have very good jump serves.
If we look only at float serves we continue to see fewer attacking opportunities after defence in the absence of the libero. In four of the five leagues, the difference is almost identical. In the fifth, Italy, it is small, but still there.
So it turns out that liberos have a measurable impact on the quality of a team’s defence after the block in men’s professional volleyball. That difference is about 1-1.5 extra attacks for every 20 defensive opportunities.
It is interesting to think about why that is, or rather how that came to be. Twenty years after the introduction of the rule, there are two whole generations of middle blockers that have never had to defend at any point in their career. And even a short visit to a top team’s practice will reveal that middle blockers almost never practice defence in any meaningful way. It is no surprise that middle blockers are worse at defence than liberos.
For a coach, the question is how we can address this structural issue in the game. Can we change how we practice to make middles better defenders? Or is it too late to turn back the clock? Can we adjust our serving and blocking tactics to make up for the defensive liability? Or is this just something that we have to live with.
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