Defensive Ability

I was recently sent a really nice article on statistics in basketball. It captures the history of the movement, but also some current fundamental issues. What it fails to do, however, is address what I will call the "Second Generation" of such analysis in the N.B.A. I fundamentally believe the problem in analysis lies in the type of data we are currently collecting. When one thinks about the box score, one realizes that it is really a type of behavioral coding system. A certain behavior occurs (e.g., player A passes the ball to player B, who quickly makes a shot without dribbling or moving too much) and a tick mark occurs on the box sheet (e.g., player A receives one assist). The problem with the box score as it is currently constituted is that it relies too heavily on discrete, positive outcomes (e.g.., player A receives no credit if player B misses his shot, regardless of the beauty of the pass) and it is relatively unsophisticated. The author in the aforementioned article ends by saying that quantitative analysis will never replace a human watching basketball footage, which is certainly true, because the data analyzed in quantitative analysis are almost entirely based on a human watching basketball footage. What the author fails to see is that this footage can be analyzed (and quantified) in more sophisticated ways, which will (likely) lead to better and more sophisticated models. It will be harder to make such a system than the extant box score (a made shot is a discrete event, but who is to say whether a post-move is "good" or not?) but if made, I believe it will launch us into the Second Generation of basketball analysis. With that in mind, I would like to develop a relatively basic coding system for defensive ability. Something simple, but better than the number of blocks, number of steals, or adjusted +/-. I would like to use this coding system for the rest of the season, see if it correlates with established metrics of good defense (e.g., opponents' shooting percentage, opponents' points/possession, etc.), and to let you, dear readers, to join me for the ride. Any takers?