- Well, in basketball just about every statistic is dependent

upon what a player's teammates do. Even rebounds are harder

to get if your teammates fail to block out the opposing

rebounders.

But we're not about to therefore stop tracking rebounds,

nor are we going to stop tracking assists. Of course, the

art/science comes in figuring out how to best utilize

those raw statistics (convert rebounds into rebounds per

minute -- but that fails to correct for FG% and game pace;

better is to convert them into rebound percentages; I suspect

that rebound odds would be best of all).

Assists are trickier than rebounds because they are indeed

highly dependent upon the performance of teammates.

But your question was already answered in NickS's original

posting, plus one of MikeG's replies:

1. If the NBA started tracking not just the good passes

that led to assists, but also the good passes that led to

missed FGAs and the good passes that led to fouls and FTAs,

we can then look simply at "good passes" (i.e. assist-worthy

passes) without worrying about the contaminating impact of

whether the passer's teammate buried the shot or not.

2. Unfortunately, we're not in that nice situation. What

then, to make of assists? NickS's work starts us on the

road to emprically figuring out the average or typical value

of an assist (I have to look at the Usenet thread that

someone cited). The other approach which is more immediately

useful is what MikeG and others have done: recognize that

while any one assist is not particularly valuable, what assists

probably do is provide possible evidence or proxies for a

playmaker's contributions. Hence MikeG pumps up their value

because an 8-assist player, compared to a 5-assist player,

is likely making contributions to the team above and beyond

those inherent in the 3 assisted baskets.

The situation is analogous to sabrmetricians trying to measure

defense. Putouts, assists, and errors by themselves are not

good ways of evaluating defense. Even the more sophisticated

techniques such as zone ratings are vulnerable to contamination

from the performance of a player's teammates (fleet or strong-

armed centerfielders taking fly balls away from their leftfield

teammates; slow-releasing second basemen costing shortstops

some deserved double-plays; etc.).

But if you're looking for some completely teammate-independent,

context-independent statistic, no you're not going to find one

in basketball. You won't find one in baseball either, but

due to the nature of the game many (not all) of the statistics

there can be made somewhat context-independent.

I'd wager that assist statistics for starting point guards

do show more of what KevinP call "stickiness" than save

statistics do for closers. In baseball, sabrmetricians

have the luxury of throwing out the save statistic entirely

and looking instead at runs prevented or DIPS or whatever.

In basketball we can't throw out the assist statistic because

then we'd have nothing (except for turnovers).

But beware of throwing out the save statistic: to simply

look at a pitcher's stats (defense independent or otherwise)

per batter faced is still failling to correct for an important

teammate- or context-dependent factor: the leverage value of

the inning. Not all innings or batters faced are created equal.

A reliever who faces three batters and mows them down in the

7th inning of a 12-0 ballgame has not made the same contribution

to victory as one who comes in with runners on the corners

in the 9th inning of a 3-2 ballgame. Some sabrmetricians are

starting to take these inning-and-score contexts into account,

but much work remains to be done.

--MKT

-----Original Message-----

From: Franklin X [mailto:xeifrank@...]

Sent: Monday, January 05, 2004 3:31 AM

Well, assist totals can be similiar from year to year or team to

team, just like the saves category in baseball, but it still doesn't

do anything about the fact that an assist is completely out of the

control of the person who gets credit for an assist. Basketball has

many stats like this, there are too many stats in basketball that are

dependent on what other people do. I admire those of you who are

able to study and quantify this stuff... :)

vr,

Xei

--- In APBR_analysis@yahoogroups.com, "Kevin Pelton" <kpelton08@h...>

wrote:> --- In APBR_analysis@yahoogroups.com, "Franklin X" <xeifrank@y...>

invented

> wrote:

> > The major problem I have with assists, is that I believe it isn't

> > a very good individual statistic. It relies too much upon what

> > another player does with the ball. Jason Kidd could get 15

> > assists, or 0 assists, it all depends on whether his teammates

> > make shots. Something Mr Kidd has no control over.

>

> I don't buy this, and here's why.

>

> In this column,

> http://www.hoopsworld.com/article_5259.shtml

>

> I took a look at the "stickiness" of various statistical skills,

> using players who played at least 500 minutes in the consecutive-

> season pairs of 00/01-01/02 and 01/02-02/03.

>

> I didn't use assist rate per se; I actually used a rating I

> I call "pass" rating -- assists^2/turnovers*minutes -- that still

gone,

> tracks assists pretty well. I found 0.889 correlation between the

> player's pass rating in Year 1 and Year 2, which was lower than the

> correlations for rebound rate and block rate but higher than the

> correlations for "shoot" (which combines free-throw and three-point

> percentages) and two-point percentage.

>

> If assists were really that context-dependent, I don't think we'd

> see this high of a correlation. Too many players change teams, and

> too many teams change players, each season.

>

> If you look at an extreme -- say, trading Gary Payton from this

> year's Lakers to last year's Nuggets -- obviously there's going to

> be a significant change in his assists. For most moves, I don't

> think the change is going to be significant. After all, Jason Kidd

> has been amongst the league leaders in assists everywhere he's

> as was Mark Jackson, to name two top passers who have moved around.

is

>

> I think a better argument against the evaluative power of assists

> the different roles players play in different offenses. Did Mike

Yahoo! Groups Links

> Bibby become a worse passer when he went from Vancouver to

> Sacramento and lost three assists off his average? No, he just had

> the ball in his hands less. Vice versa for Brad Miller.

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http://docs.yahoo.com/info/terms/ - --- In APBR_analysis@yahoogroups.com, "Kevin Pelton" <kpelton08@h...>

wrote:> --- In APBR_analysis@yahoogroups.com, "nick_scholtz" <nick@l...>

Historically, FG% and Defensive rebounds have been the best indicators

> wrote:

> > --- In APBR_analysis@yahoogroups.com, "Dean Oliver" <deano@r...>

> > wrote:

>

> > Interesting. I thought that a year or two ago there was a study

> > done on the Sonics that compared their win/loss records in games

> > when they (1) had more rebounds than their opponent (2) shot more

> > free throws than their opponent (3) had fewer turn overs than

> > their opponent OR (4) had more assists than their opponent.

> >

> > IIRC correctly, assists were by far the best predictor of wins, but

> > that study only covered one team for a third of a season.

>

> http://www.sonicscentral.com/kevin7.html

in this kind of study (see chp 6). This kind of study is, well,

flawed. Defensive rebounds are purely a reflection of fg%. So are

total rebounds, to a lesser degree. There are lots of correlations

between stats and this kind of study, while interesting, doesn't tell

you how to use the info to make teams better (my goal). Kevin points

out that turnovers aren't a huge predictor, which is true in the other

large studies I've looked at. That doesn't mean that you can tell

your team to just go out and commit turnovers. Turnovers matter an

immense amount -- but this kind of study doesn't reflect it.

DeanO

www.basketballonpaper.com