RealGM

dobrojim wrote:seems to me (and this is probably obvious to others as well)
that McGee is so confident that he can block shots that he
allows his opp to get open. Someone needs to explain to
him that defense doesn't start when his player gets the
ball.

Nivek wrote:The method is basically what Dean Oliver describes in his book, "Basketball On Paper." For those who don't know, Dean is the Bill James of basketball -- The Guru of advanced stats in hoops. Dean wrote BoP, quit his approximately $150k per year job and consulted with the Sonics for a couple years. For the past few seasons he's been Director of Quantitative Analysis for the Nuggets.

Nivek wrote:In the interest of time, I'm tracking basic stuff -- shots defensed and forced turnovers. Defensive rebounds, steals, blocks, fouls, free throws I get from the box score. Because defense is a TEAM effort, there is splitting of responsibility on various plays. So, if Wall's man dribble drives into the paint, and McGee comes over to challenge the shot, the outcome (whether it's a make or a miss) gets split between Wall and McGee.

GilShammGil wrote:
Out of curiosity, how long does it take to track a game? Seems like it must be a big investment of time considering all the detailed action you're looking at.

So in this "sharing" situation, do you give both players equal credit or blame for the outcome? Or do you try to make a judgment call as to which player shoulder's the most responsibility? I'm thinking, for example, of a play where Gil's man blows by him to the rim, but then McGee comes over and erases the shot. This results in a empty possession for the opposition, but it doesn't seem right to give Gil and McGee equal credit... is there a way to assign "blame" to Gil, but "credit" to McGee? On the other hand, if the player scores, is it fair to "blame" McGee as much as Gil? After all, Gil was the one who allowed penetration in the first place...

I can see the case for avoiding subjective judgments to keep potential bias out of the process, but I'm wondering if this could lead to misleading conclusions based on some of these team defense dynamics. What's your sense of this? Is this stuff just noise or do you think it can really skew the results you get?

montestewart wrote:^
Thanks for taking the time Nivek. Really useful data here for all of us.

A quick look at a basketball box score reveals a glaring deficiency — the info it contains about individual defense sucks. This means that half the game has long been relegated to guesswork, opinion and reputation.

The solution is straightforward: to collect new data. Since the NBA isn’t breaking speed records to track and publish defensive information, I’ve been doing it myself on and off for the past several seasons. The method is based on Dean Oliver’s defensive scoresheet, which he detailed in his book Basketball On Paper.

While in the past I’ve done some geeky tracking (including play types, court locations, tracking ball movement, steal attempts, deflections, and more), this year I’m focusing on the basics — shot defense, fouls that result in free throw attempts, and non-steal forced turnovers (such as travelling, bad passes, ball handling errors, etc.). Steals, blocked shots, defensive rebounds and total fouls come from the box score.

While it’s still too early to draw any conclusions, some patterns are emerging. Unsurprisingly, the team’s defensive troubles have been the inability to make the other team miss (a team Defensive Effective Field Goal percentage (DEFG) of .544 vs. a league average .488) and poor defensive rebounding.

The big culprits so far are the big men – Javale McGee, Yi Jianlian, Andray Blatche and Hilton Armstrong. This is no shock because bigs have the most important defensive jobs, including help responsibilities and protecting the paint. As the bigs go, so goes the defense.

McGee at least is busy, involved in a third of the team's defensive possessions when he's on the floor. He's getting a stop just 45% of the time, though and his defensive rating (points allowed per 100 possessions) is 115 (the team's is 109). McGee’s problem is that hasn't forced misses when he's not blocking the shot. His individual DEFG is .532. Compare that with departed center Brendan Haywood's .328 defg back in 04-05. Even when Haywood's effectiveness diminished a bit the past few years, his DEFG hovered around .430.

Armstrong is reasonably active (involved in 23% of the team’s defensive possessions while he’s on the floor), and he's better than the other bigs at forcing misses (.484 DEFG), but he has just one forced turnover and six defensive rebounds in 40 minutes of court time.

Yi is just awful. His defensive rating is 133. His stop percentage (a measure of how often he prevents the other team from scoring when he’s involved in a defensive possession) is .376. On 32 defensive possessions, the opposition has scored 20 times. His DEFG is .642.

Blatche has not been an active defender (involved in just 16.4% of the team’s defensive possessions while on the floor — a low number for a big). His DEFG is .578, which is preposterous for someone of his size, length and athletic ability. His defensive rating (113) is a little better than the other bigs, but in large part that’s been fueled by luck — the opposition is shooting just 3-9 from the FT line off of his fouls.Make that a more realistic 6-9 and his rating leaps to 119.

The bigs aren’t the only weakness. Kirk Hinrich plays with effort, but has not been effective. His DEFG is .598, and his defensive rating is 124. He does okay forcing turnovers (1.5 non-steal turnovers per 40 minutes), but he's generally matching up with bigger players and they're shooting over him with ease.

What's good so far? Al Thornton leads the team in DEFG and defensive rebounds. His stop percentage is .720 (meaning he prevents the other team from scoring on 72% of his possessions so far) and his defensive rating is a team-leading 65.3. He’s involved in just 12.7% of the team’s defensive possessions while on the floor, which is actually a good sign for a perimeter player (perimeter guys have fewer help responsibilities than bigs). Guys aren't getting open against Thornton, and when they shoot, they're missing.

Prized rookie John Wall is off to an uneven defensive start. He’s generating turnovers at a high rate, forcing 1.6 non-steal turnovers per 40 minutes to go along with his outlandish steals numbers. His shooting defense has been weak, and teams have targeted him. He’ll need to shore up that portion of his game to become a quality defensive player.

nate33 wrote:Jeebus. The Post will print any hack's stuff these days.