With respect to defensive statistics such as steals and blocks, we found no strong correlation between wingspan length differential and the stats themselves. In correlation coefficients, “The closer 'X’ is to +1 or -1, the more closely the two variables are related. If ‘X’ is close to 0, it means there is no relationship between the variables” according to SurveySystem.com.
In this case, 'X' would be wingspan in relation to steals and blocks. Plugging the defensive values for this past NBA season for each prospect that was eligible (incoming rookies were not), we found no value stronger than .46 for a correlation.
It doesn’t mean this data was useless in the defensive statistic regard, but it was slightly stronger for blocks and helps conclude wingspan isn’t an overriding necessity for a player to excel defensively, but it doesn’t hurt.
From a basketball perspective, it makes sense that wingspan means as much to a players game as it does in primary measurement essentials relative to height, weight, and body mass index; length is a secondary factor that supplements a prospects game, it doesn’t determine it.
Guards that have longer arms are more likely to swoop in on passing lanes and successfully pick off a pass, but being able to read the play and instinctively act on it is as, if not more, important than the extra inches on their arms.
The reason the correlation might be stronger for blocks is because of the general size and length of attempts in a confined space around the basket, whereas most steals occur on the perimeter in greater open space. The ball is generally going towards one spot on each possession (around the basket), however, steals come at more random locations during possessions.
Click here to see a bigger version of the Height vs. Wingspan Scatter Plot.