I’ve always been interested in sports statistics. Collecting and collating cricket statistics is literally amongst my first memories and was very definitely my first hobby. My interest in sporting numbers has maintained and over time I have also developed an interest in the even more interesting how’s and why’s behind the numbers. There are lots of places one can investigate the how’s and why’s of sporting numbers. Books like Scorecasting, Basketball on Paper and Wages of Wins are really interesting to follow as an intellectual exercise even if I don’t always understand completely (or care about) the details of the different sports. On the internet, Wages of Wins has a blog, and writers like Bill Barnwell and Zach Low at Grantland.com write about the NFL and NBA respectively using a heavily analytics based approach.
Volleyball, to my knowledge at least, lags a long, long way behind other sports. One volleyball analytics blog, post semiregularly but the focus is almost solely on spiking efficiency in US college volleyball. Which brings me to the point of volleyball statistics themselves. So many of them are superficial or meaningless or subjective or some combination of the those. For example, spiking percentage (kills as a percentage of attempts) provides some useful information as scoring points is the principle objective of the game. Likewise, spiking error percentage (errors as a percentage of attempts) provides information on points given up by the spiker. Spiking efficiency ((kills – errors) / attempts) on the other hand, simplifies those two numbers into one less meaningful one that overvalues minimisation of errors. None of these spiking numbers takes into account the up to 50% of spike attempts that do not end the rally. Blocking statistics are even more useless. The standard measure of blocking is blocks per set, but this figure doesn’t take into account number of attempts, number of opportunities or any number of other things. And so we can go through all the areas of volleyball.
Partly ‘inspired’ by reading the listed books and blogs and articles, I’ve tried to find different kinds of numbers that could lead to different (new?, better?) ways of understanding the game. Using Data Volley statistical software I can manipulate numbers over multiple games in a lot of different directions. A couple of things that I’ve come up with are intriguing, at least to me.
The basic area that I’ve been looking at is how particular actions impact on the likelihood of winning a point. For example, our percentage of winning the rally when we receive (sideout %) is around 69%. However, when we have perfect or positive reception (not perfect but all options available) that percentage rises to 76%. That isn’t our attack percentage after reception, but the percentage of all winning rallies in all ways. This is all logical and expected. However when I started to look at free balls (a ball crossing coming across the net without an attack) I came across something that I thought was odd. After perfect or positive free ball reception, our rally winning percentage is only 63%. Conventional wisdom says that a free ball is the easiest situation in volleyball and should lead to a very high percentage of points. But the reality is that, controlling for the quality of the first contact, we are significantly less successful than after service reception. I’m not completely sure why that should be the case. For the purposes of comparison, our opponents are also better after reception but not by as much (68%-63%).
On a similar note, I’ve been trying to thing of ways to include those 30-50% of attacks that aren’t accounted for in ‘traditional’ attacking statistics. Using a similar approach, I came up with a likelihood of winning a rally if a player attacks during that rally. For outside hitters the range is between 54% and 71%, while the middles are all between 73% and 77%. It might be interesting to note that the range of this number is much smaller than the range of spiking efficiency (54-77 versus 12-50). But then again, it might not. I’m not really sure. It seems to tell a different story about spiking, but I’m not sure if it’s a better story.
I’d be interested in your thoughts.