Not to
brag too much, but I wrote a post
recently that looks at whether the NBA’s winners benefited from tanking. It
also examined the perennial losers and showed some anecdotal evidence that they’ve
done plenty of tanking, intentional or otherwise, to little effect.
I would
not really be doing my job (not the real one, the blog one)
if I didn’t at least look at some numbers given that the blog is called “Sports
+ Numbers,” so let’s look at some numbers. AThis post is about evaluating
sequences of results. For example, we may look at where teams finish in year 0
and then track subsequent performance. Performance here will be measured mainly
in terms of winning percentage and sometimes in terms of playoff or lottery
position (e.g., 13th ranked winning percentage of the playoff teams
will be considered 13th in the playoffs, while second worst winning
percentage of the lottery teams will be considered 2nd in the
lottery).
My main
goal is to answer the following question: If a team finishes lower in the
league than they otherwise would, does it have a demonstrable effect on future
performance?
Housekeeping
I will be
looking primarily at the period beginning with the 1984-85 season because that
is the one in which the NBA introduced the Draft Lottery to make tanking less
attractive. At various points I may also take a look at the period beginning
with the 1997-98 season, because that year’s draft class was the first to be
subject to the individual rookie wage scale that, as
I have noted, is important.
The Big Picture
The first
picture we will look at is team performance in future years based on league
rank in year 0. For this analysis, year 0 will be any season from 1984-85
through 2001-02. This will allow us to look at ten years going forward from any
given season so each year will have the same 482 teams in the data set.
 |
| Sample: 1985 to 2002 |
The
picture is a bit complicated, but I love heat charts so I couldn’t resist
posting it. One thing to notice is that the deeper reds and blues – noting more
significant lows or highs, respectively, in winning percentage – dissipate rapidly
in a wedge starting with the middle teams and widening in each subsequent year.
This is what people are saying in general when they describe mean reversion.
A second
observation here is that there is fairly strong persistence of outperformance
in the NBA. This makes intuitive sense in a league dominated by superstars and
dynasties, where top players changing teams is rare enough to warrant an hour-long
special on ESPN[i].[ii]
A final,
more anecdotal, observation from the graph is that there are odd clusters. The
9th through 14th ranked teams have relatively poor
performance in years four through eight. Alternatively, the 15th
through 19th ranked teams seem to do abnormally well during those
periods.[iii]
What this
suggests to me is that we need to ditch league rank and look at relative
playoff/lottery rank. This will put a firm difference on the last playoff team
in and the first out, as the first out should get the benefit of being in the
lottery while the last in should get only the benefit of a swift beating by the
top seed in their conference (unless the top seed is the Dallas Mavericks in
2007, Seattle Supersonics in 1994 or the Chicago Bulls in 2012). Using
playoff/lottery rank will have the added benefit of normalizing worst in the
league, which was 23rd in 1985 but 29th in 2002 due to
expansion. In the playoff/lottery rank, the team with the worst winning
percentage will always be first in the lottery and the best will always be
first in the playoffs.
 |
| Sample: 1985 to 2002 |
Does Tanking Pay?
There are
two distinct kinds of tanking at issue here. Dropping from the worst playoff
team to the best lottery team or dropping from a bad lottery team down to the
worst lottery team. Any conclusions derived from this data come with the
massive caveat that two teams finishing in the same position can be very
different. An 8th seed in the Eastern Conference could,
hypothetically, be an aging team on the way down while the 8th seed
in the West is an up-and-coming young team that just clawed their way into the
playoffs for the first time. While those should average out in a large enough
data set, this is not that data set. The post-1998 sample in particular is
rather smallish for this exercise but, because it is interesting, I will keep
using it.
 |
| Sample: 1985 to 2002 |
Teams that
finish as one of the lowest-ranked playoff teams appear to perform better than
those that finish as the highest-ranked lottery teams through the next six or
seven seasons based on the 1985 through 2002 data. In the post-1998 data set,
however, the high lottery teams outperform the low playoff teams in the medium
run, recovering from an initially-depressed winning percentage to exceed the
low playoff teams in years 3 through 5. The strategic implication here would be
to tank, if possible, when faced with a seventh or eighth seed in the playoffs,
but the differences we are working with are relatively slight, three years away
and making the playoffs is worth a couple more games of revenue even in a
sweep.
 |
| Sample: 1998 to 2007 |
What about for reaaaaaaally bad teams?
This data
set can also inform our strategic decision on whether to tank to go from a 5th
to 8th position in the lottery to a 1st to 4th,
increasing the chance of winning the top pick.
According
to the data set starting in 1985, the worst teams in the league – those in the
1-4 range of the lottery – revert to .500 at roughly the same speed as the next
worst cohort. This holds up in the post-1998 data set as well. Since the
combined cut doesn’t show us anything, we need to take a look at a finer cut of
the data to see whether being the worst team and having the best shot at the
lottery makes any difference.
 |
| Beginning year 1985 to 1997, worst 8 teams only |
 |
| Beginning year 1998 to 2007, worst 8 teams only |
These two
charts look at the performance of the 8 worst teams in the league in both the
full lottery era and the post-1998 lockout era. What seems clear to me is that
there was a significant underperformance of the worst team in the 1985-1997
era. The absolute worst team stays below the second worst for the full five
years, but jumps above them in years four and five of the post-lockout set. The
team with the seventh worst record outperforms significantly, but I would
hardly go to an eighth place team and tell them to fall only one spot.
In lacking
a clear finding for the most current sample, the question of tanking answers
itself. Without giving a clear improvement in subsequent performance, is it
worth it for teams to spend up to half the season putting backups on the floor
and pissing off season ticket holders?
Going back
to my original question, I have a very hard time answering that teams do
themselves any favors competitively by finishing worse than they otherwise
would. When you figure in the short- to medium-term damage done to their fans I
would argue that tanking is a poor strategy for building a team.
[i]
Wait, most players don’t use an hour-long special on ESPN to explain changing
teams? Oh well, it’s still relatively rare.
[ii] I’m
still upset about the whole LeBron thing.
[iii]
Seriously, can we go back in time and take away his Finals MVP? If it doesn’t
go to the Refs I think Shane Battier has a better case.
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