Bucks Diary

Friday, June 27, 2008

Jefferson's defense in clear decline

As you know, this site expresses player performance according to their "Win Contribution" on each end of the court and the concomitant "Half Wins" produced as a result. Looking at the site basketball-reference.com, I notice they do a similar thing, with a bit of a twist.

B-R judges player performance according to points produced per possession while the player is on the court, with points scored refered to as the player's "Offensive Rating", and points allowed refered to as the player's "Defensive Rating" . B-R then converts those numbers into what they call "Offensive Win Shares" and "Defensive Win Shares". Each Win Share is worth a 1/3rd of a team win.

According to their system, my assessment of Richard Jefferson's offensive decline is inaccurate, but my assessment of his defensive decline is dead on. (Had we disagreed in precisely the opposite manner I would be worried. That's because my "Offensive Half Wins" system is based entirely on the work of Professor Berri, so I think I'm on solid ground with that. On the other hand, "Defensive Half Wins" are my own creation spun off from that work. Therefore I might have wavered had that been off, but it isn't.)

In fact, B-R says Jefferson had his best second best offensive performance last season, but that he also had by far his worst defensive performance. According to B-R, the Nets scored 112 points for every 100 possessions they had with Richard Jefferson was on the court, but allowed 112 points for every 100 possessions their opponents had with Jefferson was on the court. By those numbers, RJ's offensive performance was 2 points per 100 possessions better than his career average, but his defense was a whopping 8 points per 100 opponent possessions worse than his career average.

And their numbers say Jefferson's defense has been in free fall the last two seasons. In the 2005-06 season he had a defensive rating that matched his career average, 104 pts/100 possessions, then in 06-07 that dropped to 109 pts/100 possessions, and then this year of course it dropped even further to the 112 pts/100 possessions I cited above.

This might not be horrible news though, Antlerheads. In fact, I actually hope their numbers are more accurate than my own. That's because I think Skiles can probably coax a defensive renaissance out of Jefferson, but I'm not sure he can do the same for his offense.


At June 27, 2008 at 6:44 PM, Anonymous Anonymous said...

I don't think Berri's numbers are meant to be split into offensive and defensive "scores" the same way as the ratings on B-R. DRtg probably uses the defensive statistics (ie. defensive rebounds), while omitting the offensive, and vice versa for the ORtg. Win Score however, takes into account all defensive and offensive stats, so in effect it is already determining the net contributions of the players.

Interestingly, win shares and win shares above average (WSAA) are highly correlated to WP48 because it is using both the DRtg and ORtg to rate the overall effectiveness of a player. For example it rates players like Carl Landry highly, while lambasting guys like Kevin Durant.

At June 27, 2008 at 9:47 PM, Anonymous Anonymous said...

Continuing the Bucks' proud tradition of bringing in name players past their prime? 2008, this one ranks well below Oscar, Lanier, Moses, and Sikma. That's going too far though, at least while it's still summer. After all we traded maybe our 4th and 10th best players for someone who'll probably be our 3rd or maybe 2nd best unless his leg falls off.

It's true as Paul said about who else would take Simmons?... Also on the other side, how many other teams beside the Bucks would want Jefferson's contract given his trends? But to me right now it seems downright reasonable at first glance, compared to most of the crap we're stuck in.

Now that 2nd/3rd best makes me think... damn that 23-4-3 looked familiar... fuckin a look how close their numbers were last year, tell me if you don't marvel at that a little bit. It should make me feel better but I think it makes me feel worse. At least this one is over $8 million cheaper for the next three years.


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