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Thursday, December 09, 2010

Flawed Box Score Numbers Can Lead to Faulty Conclusions

It has been a while since I charted a player's assists for an entire NBA game but a play from Boston's 105-89 victory over Denver on Wednesday night caught my eye: Rajon Rondo passed the ball to Ray Allen in the right corner, Allen took two dribbles, drove from behind the three point line to the hoop, made a contested left handed layup--and Rondo received an assist! While it is true that technically an assist can be awarded even if the shooter dribbles after receiving the pass, an assist is supposed to be a pass that leads "directly" to a score. There is nothing special about making a routine pass to the corner and watching a future Hall of Famer execute an excellent move. An assist is supposed to reward the passer for helping to create a shot, not for simply being the last player to handle the ball before someone else shoots.

Some people may dismiss my concerns about the authenticity of NBA assists by looking at players' home/road splits, arguing that this all evens out, but I reject that contention for two reasons:

1) I have never suggested--and do not believe--that the primary problem is "home cooking"; I think that the assist standards have been lowered across the board (even though the official definition of an assist has not been changed) and I also strongly suspect that scorekeepers are more apt to give borderline (or even bogus) assists to players who are perceived as elite playmakers than they are to players who are not perceived that way. In other words, if Glen Davis had made the pass that Rondo made to Allen I doubt that Davis would have received an assist, even in Boston. The reason I say this is that if assists were handed out on every such play then almost every field goal in the league would be classified as an assisted field goal and that is not the case, though the number of assisted field goals has trended upward in recent years--a strange phenomenon considering how much of the NBA game consists of post up plays and isolations.

2) If, as I suspect, elite playmakers receive a certain benefit of the doubt across the board then things do not really even out over the course of the season--and this should be a great concern to both "old school" journalists/historians as well as to the "stat gurus."

This type of thing is one reason that I do not trust "advanced basketball statistics"; the "stat gurus" create formulas that not only contain various flaws/biases but they are also using basic numbers (i.e., box score statistics) that are not completely reliable. As I have said many times, it is much more valuable to have a player who draws a double team and makes the correct initial pass that ultimately leads to an open shot on the weak side than to have a player who racks up high assist totals because he handles the ball all of the time and/or he benefits from lax scorekeeping standards.

I thought that Chris Paul was the best point guard in the NBA a couple years ago even though my research strongly indicated that his assist totals were heavily inflated and I think that Rajon Rondo is one of the best point guards in the NBA now even though I don't believe that he is legitimately averaging over 14 apg--but until the NBA vastly improves its scorekeeping standards I will look with a jaundiced eye at the most subjective box score numbers (assists, steals, blocked shots, turnovers) and I will also be most suspicious of "advanced basketball statistics" that are based on those faulty numbers.

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posted by David Friedman @ 4:37 AM

6 comments

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6 Comments:

At Friday, December 10, 2010 12:17:00 PM, Anonymous Anonymous said...

marcel

i always thought a assist was one player passes the ball to a player, if he doesnt pass the ball and he scores thats a assist. but i guess he cant dribble so like a out let where its a catch and finish or alley oop is a real assist. rondo getting 14 apg pretty good paul was getting 11 a couple years. but your right on the rule, they delegitimized it thats bad right there.

 
At Friday, December 10, 2010 1:53:00 PM, Anonymous dsong said...

I think assists are a deceiving statistic, but for a different reason than you cite. I've been always wary of point guards with high assist averages because it usually means they're hogging the ball - the offense grinds to a halt as the point guard dribbles up and down at the top of the key for 10 seconds, and the "offense" consists of the point guard passing to some guy who shoots the ball.

I prefer to see an offense where all five people pass the ball around. That's where the triangle offense comes in - all five people are asked to make plays on any given possession. You won't see one guy rack up 10-15 assists, but you will see greater offensive efficiency.

Also note that star point guards aren't necessarily conducive to winning championships. I can count the number of superstar point guards who led his team to championships on one hand. It's a myth, just like the myth that you need a "dominant big man" to win championships.

 
At Friday, December 10, 2010 2:57:00 PM, Blogger David Friedman said...

Marcel:

The recipient of an assist pass can dribble but only if he has an unimpeded path to the hoop--one example would be a player getting a defensive rebound and throwing a long outlet pass to a teammate who catches the ball and dribbles in for an uncontested layup; if the shot was not contested then the passer gets an assist no matter how many dribbles the recipient took. That reasoning does not apply to the Rondo-Allen play that I cited, because Allen drove around a defender and took a contested shot; Allen created the shot, not Rondo.

Rondo and Paul are both great passers but I have no idea how to compare their assist averages with the assist averages of the great players from the past because of the obvious assist inflation that is taking place now.

 
At Friday, December 10, 2010 3:11:00 PM, Blogger David Friedman said...

Dsong:

I agree that it is not necessarily beneficial to have a point guard (or any player) who racks up assists by monopolizing the ball; this criticism is not new and has been made about players as diverse as Oscar Robertson and Kevin Porter. Robertson is obviously an all-time great and vastly superior to Porter but it is worth noting that Robertson did not win a championship--or even reach the Finals--during all of his years of dominating the ball for the Cincinnati Royals (admittedly, the Royals faced some pretty stiff competition, including the dynastic Celtics).

I have already said that the Heat would be well served to establish some kind of offensive system that is more sophisticated than LeBron "getting his" followed by Wade "getting his" and everyone else picking up table scraps. Phil Jackson has successfully employed the Triangle not with the idea of creating shots for his stars but rather with the idea of involving the other players in the offensive attack.

The last point guard who led a team to a championship while ranking in the top ten in assists is Isiah Thomas (1989 and 1990).

It used to be true that a team had to have a dominant big man to win a championship and for nearly a decade and a half only centers won the NBA's regular season MVP (from Robertson in 1964 to Erving in 1981) but rules changes and style changes have reduced the importance of having one dominant big man, though a championship team still must have effective inside players (particularly on defense).

 
At Sunday, December 12, 2010 12:53:00 PM, Anonymous Matthias said...

Do you think there are differences in assist counting between pg like rose, rondo, paul, nash, kidd, etc.? Who does the counting? Is it a local of L.A., Chicago, etc. or do they travel like the nba-referees where ever the nba choses?

What do you think about the top 4 of the east- and west-conferences? Are there any surprises for you until now?

Matthias

 
At Sunday, December 12, 2010 10:24:00 PM, Blogger David Friedman said...

Matthias:

The home team provides the official scorekeeper for each game. As I mentioned in this article, in previous seasons I have charted assists for a handful of games and noticed that assists are handed out too generously; I have never found an example of an assist that should have been awarded but was not but I have found many examples of the opposite. It is my untested hypothesis that elite point guards and other players who monopolize the ball receive more favorable treatment regarding assists than do players who are not known as playmakers--but, whatever the reason or reasons, it is clear that assists are a very, very subjective statistic as currently tracked by the NBA.

If the season ended today then I would have predicted three of the top four East teams correctly; I had Chicago fifth but they are currently fourth, while Milwaukee (my choice for fourth) is currently eighth. The Bucks have not been as good as I expected. The Knicks are better than I expected, while the Cavs started off like I expected but are in the middle of a horrendous losing streak.

I correctly picked the top four in the West as things currently stand (though I ranked those teams in a different order). The Spurs have surprised a lot of people but I expected them to pose the most serious threat to the Lakers in the West. Houston is playing worse than I expected but some of that is because of Yao's injury.

 

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