In anticipation of tomorrow night's (7:00 Eastern) NCAA men's championship match between Penn State and Stanford, the Nittany Lion athletic department has put out a press release that includes some interesting statistical facts.
According to the release, Penn State is 21-6 when two or more players record double-digit kills, 7-3 when two or more players record double-digit digs, and 13-2 when achieving 10 or more blocks (among other things). Such statistics can potentially provide useful insights in assessing a team's chances of winning a particular match. However, caution should be exercised for a few reasons. Before I go any further in my comments, though, I want to state that I am thrilled any time I see statistically oriented writing in the coverage of volleyball and that I intend my remarks in a constructive spirit.
First, the presented statistics do not make use of all the known information. Using the last statistic given above, the Nittany Lions are 13-2 when getting 10 or more blocks. What is their record when getting fewer than 10 blocks? As shown below, we can fill out the picture by knowing that the team's overall record is 24-7.
With all of the cells filled in, we can thus see that Penn State has a pretty good record, too, when getting fewer than 10 blocks.
Second, there is considerable variation in the quality of Penn State's opposition during the season. Playing other eastern (or midwestern) schools presumably is not as difficult as going against the traditional Mountain Pacific Sports Federation powers the Nittany Lions faced during the regular season (USC, Hawai'i, UC Irvine, BYU, Cal State Long Beach, UC Santa Barbara, and Cal State Northridge). As accessed from Penn State's game-by-game log, here are the Nittany Lions' total blocks (in red) and match outcomes against MPSF opponents:
USC 4 L(0-3)
Hawai'i 16 W(3-2)
UCI 9.5 W(3-2)
BYU 6 L(1-3)
CSULB 5 W(3-0)
UCSB 6 L(3-0)
CSUN 8.5 L(3-0)
As shown, only once in these seven matches did Penn State achieve 10 or more blocks, and it happened in a five-game match, which provides more opportunity to accumulate blocks (and other statistical markers). Blocks per game might be more appropriate to cite.
Of course, though, in a stunning turnaround from Penn State's 0-3 loss at Cal State Northridge on April 10, the Nittany Lions turned things around on Northridge in last night's NCAA semifinals, winning 3-0 on the strength of 11 blocks. Eleven blocks in three games yields a robust 3.67 average. Penn State's opponent in the championship game, Stanford, piled up 12 blocks in a three-game sweep over Ohio State.
Lastly, as is drilled into the heads of all students taking social-science research methodology courses, correlation (i.e., that two things co-occur) does not by itself prove that one thing has actually caused the other. In basketball, for example, one might find that when a given team makes under 10% of its three-point attempts, it loses the game a high percentage of the time. One might intuitively interpret such a statistic to mean that poor shooting caused the team to lose. However, the team could have been trailing in some of its games for reasons having little to do with three-point shooting and then taken a lot of desperation threes (that were missed) in an attempt to get back into those games. In other words, it may have been the losing that caused the missed shots from behind the arc. Similar examples for football are discussed here.
I could envision a volleyball scenario where a team would have a poor won-loss record in matches in which it committed a large number of service errors. Maybe the service errors cost the team a lot of points early and paved the way to eventual defeat. But, it could be that the team fell behind for reasons unrelated to serving and then decided to serve aggressively in an attempt to catch up, only to have the high-risk/high-yield serves mostly fail. Something to think about.