Review by Tom Lyons
“Basketball on Paper” is a recently published book (Brassy's, Inc.
2004) that attempts to use statistical analysis to distinguish what is
truly important to winning basketball games. The book also provides ways
to analyze individual player performance. The jacket describes the
author, Dean Oliver, as “a former basketball player, assistant coach,
and collegiate scout” who founded the online “Journal of Basketball
Studies” (www.rawbw.com/~deano/) and who has contributed to
Basketball Digest
and the Association for Basketball Research. Oliver attended college,
played basketball and coached at Cal Tech. He has a Ph.D in engineering
from North Carolina. Oliver worked for Bill Bertka's scouting service
for four years. He has paid the bills as a computer consultant and risk
analyst. Oliver is now with the Seattle Supersonics putting his
basketball theories into practice. (As of the 2005 All-Star break, the
Sonics were 35-15 and 10 games up in the new Northwest Division. Last
year, they finished 40-42, 19 games back in the Pacific Division).
Referring to Michael Lewis' book about the Oakland Athletics' use of
statistical analysis to run their team, Oliver has called his book the
“Moneyball” of basketball.
It is to some extent a compendium of material previously published on
his website or elsewhere. One article on the website seems to be a
revision of one chapter of the book. It is well written and appears to
be a very thorough attempt to use a lot of data, mostly from the NBA,
and, in some cases, very complicated formulas
*
to arrive at its conclusions. In that sense, the full-blown analytical
methods themselves are not very useful for coaches unless you have a ton
a data about your team and individual players as well as the ability to
draft a computer program that uses that data. The book provides a
detailed explanation of how to record data about a team manually. Oliver
says on his website that he has developed an analytical program named
“Roboscout” that he uses with the Sonics but it is generally not for
sale.
Oliver believes his conclusions apply equally well to women's
basketball, but he does not have the wealth of data there that he has
for the NBA. Oliver has some WNBA data and states he is involved in a
long-term project analyzing WNBA data but he does not have many
conclusions from that analysis yet. Nonetheless, nothing in the data he
has indicates his conclusions do not apply to women's basketball. His
conclusions are useful and enlightening, at least to me. (Even if you
already know them, you can now say science confirms them). Here are
Oliver's main points.
Based on statistical analyses, the four most important keys
for team success in basketball and their relative weights, in
parentheses, are:
- Shoot a high field goal percentage (10).
- Do not commit turnovers (5-6).
- Get offensive rebounds (4-5).
- Get to the foul line frequently (2-3).
Teams that consistently win basketball games do at least three of these things well.
If a team doesn't shoot well, it better do the other three things very
well. I should note that Oliver says these factors should be considered
on the basis of the number of a team's possessions compared to its
opponent, not in absolute terms. In other words, he looks at efficiency,
for example, the number of made shots per possession, or the number of
turnovers per possession, not total points or turnovers, which can vary
greatly depending on the pace of the game.
Obviously, these keys could also be stated from the defensive
perspective, i.e., prevent easy baskets, cause turnovers, do not give up
offensive rebounds, do not foul, etc. However, I have put them in the
offensive perspective because of another of Oliver's conclusions: In the
NBA, at least since the 1970's,
offense wins playoffs and championships more often than defense
. The difference in success between strong offensive teams and strong
defensive teams is not large, but the data contradicts the old adage
that defense wins championships. I suspect this may be even more
accurate at lower levels of basketball where offensive skills are more
rare than defensive skills. [On the other hand, in a one-game playoff,
it is possible for a team or a critical player to have a bad shooting
night, whereas defense may not be as variable].
But, if defense does not necessarily win championships, where did the
idea originate? With Bill Russell's Celtics who were the best
defensive team ever and won 11 of 13 championships during his tenure.
They had Hall-of-Famers coming off the bench. Of course, basing the
idea on those Celtics is like looking at Michael Jordan's Bulls who won 6
titles in 8 years and saying shooting guards win championships. The
fabulously exceptional team or player is still the exception.
Oliver offers some comments on why he thinks these factors appear so
important. The benefit of a high shooting percentage is obvious,
especially since most missed shots result in defensive rebounds (and
potential fast breaks). Oliver cites one study that found that the NBA
team with the higher field goal percentage won 79 percent of the games.
Turnovers are important because a team cannot even shoot, never mind
score, if it turns over the ball during a possession. The NBA team with
fewer turnovers wins about 58 percent of the time. If field goal
percentages are about equal, the team with fewer turnovers wins 69
percent of the time. In an email to me, Oliver commented that turnovers
are even more important below the NBA level.
Offensive rebounding can make up for a poor shooting percentage,
particularly as shots off of offensive rebounds generally are more
likely to result in scores than initial field goal attempts. Oliver
refers to a study of WNBA offensive rebounds done by an official with
the Charlotte Sting. The study found that offensive rebounders increase
their field goal percentage from 41 to 48 percent and their points per
play from about .80 to .94. That improved the team's points per play
from .80 to .90, which Oliver says is a huge difference. In the NBA, if
shooting percentages are about equal, the team with more offensive
rebounds wins 63 percent of the games. (This also emphasizes how
important it is for the defense to box out).
Oliver discounts to some extent the value of defensive rebounding. He
notes that 70 percent of missed shots result in defensive rebounds so
they do not take much special effort or ability. Also, defensive
rebounds are to a large extent the result of good defense making the
offense shoot a low field goal percentage. In that sense, factoring in
defensive rebounds is like double-counting the same affect.
Interestingly, it is more important for teams to get to the foul line
frequently than it is for them to hit a high percentage of their foul
shots. Perhaps, this is because lots of foul shots means the other
team's starters are in foul trouble. Again, if shooting percentages are
equal, the NBA team that commits fewer fouls wins 67 percent of the
games.
Oliver also has some other observations based on his NBA data.
Good offensive players are more important than good offensive systems.
Oliver offers numerous examples of good scorers who succeeded
regardless of the system in which they played and “good” offensive
systems that floundered without a good scorer(s). Think of the Bulls'
triangle offense with and without Michael Jordan. Think of Shaquille
O'Neal in Orlando and Los Angeles. On the other hand, Oliver does note
that a few NBA coaches have had offensive success with more than one
team: George Karl, Phil Jackson and Don Nelson. This may be because they
are good at recognizing and using scorers well, not necessarily because
of any particular system. In other words, adapt the system to the
players rather than vice-versa. However, I should note that Oliver
believes offensive systems are more important at the college ranks and
below but he cannot prove it.
Offensive efficiency is more important than pushing the pace of the game.
Oliver quotes Dean Smith who said: “The biggest reason I'm against
simply running the ball down and shooting the first shot available is
that the defense doesn't have time to foul you.” And, as noted, getting
fouled and shooting lots of foul shots is a key to success. Slowing the
game (reducing the total number of possessions) down does not seem to
increase defensive efficiency (the percentage of stops), though, as will
be described below, it does make the outcome of individual games more
variable.
Good offensive teams have both inside and outside scoring, however, no single position is key to offensive success.
A team does not have to have a great point guard or a great center to
score efficiently. However, it does have to pass well. Most offensively
successful teams have a high percentage of assists on their scores.
Assists lead to higher quality shots and a higher shooting percentage.
The NBA team with the higher number of assists wins about 72 percent of
games.
Height is more important to offensive success than defensive success, though it is not critical.
Statistically, the top offensive teams in the NBA have been somewhat
taller than average, whereas the top defensive teams have been shorter
than average. [Of course, the reason could be that shorter teams had to
play tougher defense because they had a hard time scoring]. While there
is a correlation between having a top shot blocker and having a very
efficient defense, there is no correlation between a high team total of
blocked shots and defensive efficiency. Oliver surmises that height may
be more important at the high school and college level where there are
greater variations in size among the players.
Contrary to what some coaches and commentators think, it is not easier for offenses to rebound three point shots.
Oliver looked at numerous NBA games between 1999 and 2002 that included
several thousand missed shots. The offense rebounded 33 percent of two
point misses and 31 percent of three point misses. Generally speaking,
the rebounds on three point shots do not go farther from the basket than
two point shots. Also, many two point field goals are shot close to the
basket and the shooter often has the best chance to get the rebound.
There is no such thing as a “hot hand.” Oliver cites
two studies of NBA players and one of college players that showed no
indication that any particular players were more likely to make a shot
if they had made the previous shot. The NBA studies were of the
Philadelphia 76ers' field goal attempts during the 1981 season and the
Celtics free throw attempts during the 1981 and 1982 seasons. If
anything, the players were slightly more likely to make a shot if they
had missed the previous one. Of the twenty-six college players only one
was significantly streaky.
Underdogs should adopt a “risky” strategy even if no particular strategy is clearly better.
A risky strategy is one that changes the dynamics of how the game would
normally go. Examples of risky strategies are pressing, attempting many
three point shots, slowing down the pace of the game, playing a zone,
fronting the post, sending guards to the boards to rebound, releasing
the guards on defense for a potential fast break, and playing oversized
or undersized lineups. If one such strategy is clearly better, such as
pressing a tall team with poor ball-handlers, then the underdog should
use that strategy. However, even when no particular risky strategy is
better, the underdog should still use one.
Oliver notes that the slow down strategy works by reducing the number
of possessions each team has. This reduces the better team's advantages
and makes the outcome more variable. Similarly, the other risky
strategies make results more variable in different ways. For that
reason, the otherwise superior team should avoid risky strategies.
Oliver describes how Rick Pitino's talented Kentucky teams may have lost
some games by pressing.
With respect to evaluating individual player's performances, Oliver
says the goal is obviously to determine how well a player helps a team
do the things that win basketball games. From an offensive perspective,
the player should:
- Shoot a high field goal percentage or help teammates shoot a high percentage through assists and playmaking.
- Avoid turnovers.
- Get offensive rebounds.
- Draw fouls.
At the defensive end, the player should:
- Make offensive players take low percentage shots.
- Cause turnovers.
- Box out and prevent offensive rebounds.
- Avoid fouls.
Oliver discusses several different ways of evaluating individual
offensive and defensive performance including his own methodology.
Suffice to say, most of them, including his own, require much detailed
data about what a player does in the game and a good computer program.
However, if a coach does not have those resources, she can still pay
close attention to these four factors.
Even using Oliver's methodology, individual defensive assessments in
particular require a lot of subjective judgment. Which defender gets
credit for causing the offense to take a bad shot, especially if the
defense is in a zone? Which defender caused a turnover, the one
harassing the passer or the one who stole the pass? Who failed to box
out the offensive rebounder? Whose fault is it if a help defender picks
up a foul? Should the credit or blame be split between two defenders?
And, to what extent does the coach want to delegate that judgment to
someone else?
Team chemistry is very important though it is more difficult to quantify.
Chemistry has two parts: having a team that has well-balanced skills
and having players who are willing to contribute to the team's good
balance. If you already have several good shooters, you may need more
ball-handling and defensive skills, otherwise, you will have too many
turnovers and give up too many points. On the other hand, if your team
dribbles and defends well, but cannot put the ball in the basket, you
need shooters. Oliver discusses some statistical analyses to determine
your team's needs.
The second part of chemistry, players with good attitude, is very
important but very difficult to quantify. Oliver says that an important
issue is giving players credit for the contributions they do make. He
describes psychological studies about people's concepts of “fairness”
that are not purely rational. He notes that very few players are willing
to play on a team where one player takes all the shots and gets all the
credit no matter how much better he or she is than the others. Good
coaches have to find ways to balance players' abilities and give credit
to maximize individual efforts and team success.
While the second part of Oliver's book may not provide much specific
help to coaches who lack a substantial support staff, it does provide a
lot of fodder for basketball buffs to debate. He has a huge amount of
statistical analyses of individual players. The first part of the book
has a large amount of data comparing NBA teams, past and present. For
example, his analysis indicates that the most dominant professional
basketball player in the last 25 years is not Michael Jordan, it is
Cynthia Cooper. (Who volunteers to tell Mike?). Arguably, the single
best offensive season for a male professional player in that period
belongs to…..Reggie Miller in 1991. As great as he was, a good argument
can be made that Jordan did not shoot the ball enough. Ditto for Cooper.
Allen Iverson should shoot less. Who was a better NBA player, Bird or
Magic? Well, statistically, it's a dead heat, for second place, behind
Jordan. The top offensive NBA teams, compared to their competition, have
been the Denver Nuggets of 1982, the Chicago Bulls of 1997 and the
Dallas Mavericks of 2002. The top defensive teams were the Knicks of
1993, the Bullets of 1975 and the Jazz of 1989. Cooper made the Houston
Comets simply unbeatable at either end of the court.
Oliver's book and website are very useful for coaches at all levels.
Coaches who have the resources to gather substantial data on their teams
and opponents and analyze it will have very helpful information. They
can use that to evaluate their players, pick optimal offenses and
defenses for their teams and decide good match-ups or combinations of
players on the courts. Even coaches who do not have those resources can
use this information as guidelines for making more intuitive decisions.
