Recently, I was having a debate with my roommate over the value of shot-blocking. I was arguing that it was a good stat to measure exactly what it pertains to (blocked shots), but that it doesn't necessarily illustrate if a player is a good defender. Of course, I conceded that some of the league's best defensive big-men -- Dwight Howard and Andrew Bogut are the ones I mentioned -- are at the top of the BPG leaderboard. However, I claimed that there were several players with high block-totals that weren't good defenders. I pointed to JaVale McGee, Amare Stoudemire, Al Jefferson and Brook Lopez as examples of players who blocked a lot of shots, but were below average defenders. I was curious to see where these players fell on this year's leaderboard, but I was surprised with what I found. McGee, Stoudemire and Jefferson were all in the top-10, but I had to scroll down to #22 to find Brook Lopez. As hard as I am on Lopez for his lack of toughness, effort and basketball IQ on the defensive end; I had always credited him with being an above average weak-side defender and good shot-blocker. So, it was a surprise to find him with such a low block rate for the season.
After being surprised with Lopez's lack of shot-blocking, I wanted to check his career numbers to make sure I hadn't been overstating his block rate (subconsciously) in the past. What I found wasn't encouraging -- Lopez's shot-blocking had regressed each year of his short career. In his rookie season, Lopez posted a BLK% of 4.9; in his sophomore season, 3.4; and this season, 3.2. It was bizarre -- usually you see players become better shot-blockers as they mature because they learn to take better angles -- so I began to theorize the possible cause(s).
My first thought was that the culprit could be Lopez's concerted effort to avoid getting into foul-trouble; because he knew his team needed him to produce on offense. I expected to find that his foul-rate would be significantly lower in each progressive season, but the disparity wasn't large enough to suggest such a thing. In his rookie season, he committed 3.7 fouls per 36 minutes; in his sophomore season, 3.0; and this season, 3.0. Although his foul rate was higher in his rookie year than the past two seasons, it wasn't high enough to suggest that he was taking huge risks on the defensive-end. Plus, rookies have a higher propensity to commit fouls because they have trouble getting in rhythm defensively.
Next, I speculated that Lopez had played alongside a better shot-blocker in his past two seasons, who could, in effect, steal potential shot-blocks (similar to the way Humphries lowered Lopez's rebounding total). But after looking at the BLK% of players that Lopez played with, it didn't seem like large enough of a discrepancy to effectively conclude that it was the cause.
The only theory I had left, was that Lopez's bout with mononucleosis was somehow at fault. However, I couldn't formulate a concrete result from the illness which could lead to his decrease in shot-blocking. It also wouldn't explain the decline that he suffered during his sophomore season.
So ... I'm stuck. I was curious to hear if anyone could formulate a viable cause for such a decrease. Why would his shot-blocking decrease as drastically as it has?