Saturday, February 9, 2008

Tradeoff of Serving Aggressively (or Cautiously): Service Errors vs. Aces

The other night, I caught a replay of UCLA hosting USC in men's volleyball, on Fox College Sports. It was the second match of the season between the Bruins and Trojans. In the first match, as the TV announcers pointed out, the teams had combined for 51 service errors, so it was suggested they would be toning down their aggressive service in the rematch. Indeed, UCLA and USC cut their combined service errors in half, to 25, in the second match.

That got me to thinking about coaches' decision-making strategies involved in choosing whether to have their teams serve aggressively or cautiously. The most aggressive type of delivery would seem to be the jump serve, as illustrated in these brief video clips I found on the web (here and here).

Such a serve has the potential to generate an ace or, if not that, a ball that the receiving team struggles to retrieve and thus takes the team out of its offense. Trying to pulverize the ball on the serve also, however, creates the potential for a missed serve, either into the net or out-of-bounds long. Jump-serving truly seems to be a high-risk/high-yield proposition (see here for a general discussion of risk/return tradeoffs, from the perspective of investing).

Additional web-searching turned up a 2000 American Volleyball Coaches Association (AVCA) newsletter article on serving, written by Melissa Stokes, who this past fall completed her 12th year as women's coach at Missouri State (formerly known as Southwest Missouri State).

The article by Stokes covers serving strategies and practice drills, with a healthy supply of statistics thrown in (probably from 1999). Using stats from the Missouri Valley Conference (in which her team plays), Stokes reveals that though her team was not among the league leaders in aces per game, it kepts its service error rate very low, resulting in virtually a 1-to-1 ratio of aces and errors. In contrast, there were a few MVC teams whose error-to-ace ratios were roughly 2-to-1. Stokes commented that:

Every team will have a different serving philosophy. This chart shows you that these statistics support our serving philosophy. We may not have posted as many aces, but committing fewer errors allowed our players the opportunity to score points at the net or by playing defense.

My curiosity sufficiently piqued, I then went and found the boxscores for the two UCLA-USC men's matches (both of which, incidentally, were won by the Trojans).

UCLA at USC (January 23, 2008, 5 games)
UCLA: 11 aces (2.2/game), 30 errors (6.0/game)
USC: 3 aces (0.6/game), 21 errors (4.2/game)

USC at UCLA (February 6, 2008, 3 games)
UCLA: 3 aces (1.0/game), 11 errors (3.7/game)
USC: 4 aces (1.3/game), 14 errors (4.7/game)

Speaking in approximate terms, UCLA's rates of aces and service errors each were cut in half from the first to the second match. This kind of proportionality is what I would have expected. USC doubled its rate of aces (albeit from a low baserate), but only experienced a slight proportional rise in errors.

These are just some limited examples, but I hope this posting can spur an expanded discussion of serving tradeoffs.