Over an 82 game season, the Boston Celtics won 29 more games than the Atlanta Hawks. Given this disparity, people expected the Celtics to easily defeat the Hawks in the first round of the playoffs.
But that didn’t happen. The Celtics were the only advancing team to be pushed to seven games in the first round. Such an outcome led to the following observations from people connected to the Atlanta Hawks (first two quotes from a Mark Bradley article in the Atlanta Journal-Constitution, while the Josh Smith quote is from a D. Orlando Ledbetter article in the AJ-C).
“We played a great series,” said Michael Gearon Jr., one of the team’s several owners. “We established some respect for ourselves around the league. Are we disappointed to lose? Absolutely, but it doesn’t take away the direction we’re going, and that’s to be a premier team for a long period of time.”
Said [Mike] Woodson: “[The series] definitely changes the perception. … I think our fans like our product, and it really doesn’t get much better than those three games in Atlanta. … Basketball is back in Atlanta in a big way.”
“You’ve got to find some positive out of it, and you know we came further than what people thought we were going to do,” [Josh] Smith said. “Now they understand that the Hawks are a good team. We play hard and we try to bring it every night.”
Smith believes that he and the Hawks did garner some respect for their play against the Celtics.
“I’ve got confidence in my team, confidence in my teammates,” Smith said. “I know that if we play hard and if we play to the best of our capabilities that we can play with anybody.”
From the owner, to the coach, to the starting power forward, the same story is told. The Hawks are now a “good” team. But is the data consistent with this perspective?
Evaluating Atlanta’s Regular Season
We now have two data sets on the Hawks: the 82 game regular season and seven playoff games. As I have noted in the past, I think we should prefer a bigger sample to a smaller sample. When we look at the regular season, do we find that the Hawks have improved?
To answer this question, let’s first look at what the Hawks did in 2007-08 and over a collection of recent seasons.
The Hawks in 2007-08 won 37 games with a -1.92 efficiency differential (offensive efficiency minus defensive efficiency). And here is a collection of recent results:
1999-2000: 28 wins, -5.64 Efficiency Differential
2000-2001: 25 wins, -5.51 Efficiency Differential
2001-2002: 33 wins, -4.45 Efficiency Differential
2002-2003: 35 wins, -3.76 Efficiency Differential
2003-2004: 28 wins, -4.90 Efficiency Differential
2004-2005: 13 wins, -10.22 Efficiency Differential
2005-2006: 26 wins, -5.06 Efficiency Differential
2006-2007: 30 wins, -5.07 Efficiency Differential
From 1999-2000 to 2006-2007, the Hawks averaged 27.3 wins and posted an average differential of -5.58 (if we ignore the 2004-05 season the averages are 29.3 wins and a differential of -4.91).
Relative to these averages, the Hawks of 2007-08 improved by less than 10 wins. So Atlanta was better, but not by much.
Finding Improvement in Atlanta
Where did these additional wins come from? The answer to that question is reported in Table One.
Table One: The Atlanta Hawks in 2007-08
If we take the rookies performance as given (so Al Horford’s performance is not forecasted), we see in Table One that the Hawks – given what the veteran players did in 2006-07 – should have expected to win 32 games this season. The Wins Produced from this season, though, sum to 36.3. So the Hawks veteran players improved by only four wins. And this improvement was primarily confined to just two players: Marvin Williams and Anthony Johnson (who is no longer on the team). Joe Johnson, Josh Smith, Mike Bibby, and Josh Childress were essentially the same players in 2007-08 as we observed in 2006-07.
Given such little change in the productivity of Atlanta’s veterans, it must be the case that this team simply improved because it drafted Al Horford. Horford produced 9.0 wins in 2007-08, the top mark among all rookies. And it was this production that got this team into the playoffs. In other words, the team didn’t make the playoffs because of better team chemistry, or better coaching, or just because it tried harder. The team drafted Horford (one of the better players in college last season), and his production added to what the veterans on this team were already offering was good enough to get the team to a mark that was slightly below average.
Searching for More in Atlanta
The analysis so far has focused on the entire team. If we look at the players who played at least 1,000 minutes for Atlanta this year, we wouldn’t expect to see a below average team. From Table One we see this team fields the following starting line-up (WP48 listed after each name):
PG: Mike Bibby (0.107)
SG: Joe Johnson (0.100)
SF: Marvin Williams (0.043)
PF: Josh Smith (0.111)
C: Al Horford (0.170)
The average WP48 of this group -despite the play of Williams — is 0.106 (which is slightly above the average mark of 0.100). Josh Childress – the top player off the bench – has a WP48 of 0.206. So with Childress, we see six players with a 0.123 average WP48. Such a mark is consistent with a 50 win team.
So why are the Hawks below average? It turns out that every other player employed by Atlanta this season had an average WP48 of -0.009 (excluding Anthony Johnson you get a mark of -0.042). In sum, the Hawks were held back by a very weak bench. Obviously if Atlanta could fix that problem, this team could actually become a serious contender in the Eastern Conference. Or to repeat the argument stated earlier, the Hawks simply need to add a few more productive players to get better. Hoping for better chemistry, better coaching, and/or more effort is probably not going to get it done.
Commenting on the Playoffs
Let me close by commenting briefly on the smaller sample noted earlier. The Hawks did take the Celtics to seven games. But if we look at the aggregate playoff stats, the Hawks did not play well. The team’s efficiency differential in the playoffs was -13.51. Obviously when you are out-scored by 12 points per contest, your differential is not going to look to good.
When we look at the individual players, we see two Atlanta players with a PAWSMIN (Position Adjusted Win Score per minute) that was above average. Josh Childress and Al Horford – the two most productive players in the regular season – were the only players to be above average in the post-season. Such a result is consistent with what we generally see in the playoffs. Players tend not to rise to the occasion in the playoffs. What we tend to see is that good players in the regular season are good (although not as good) in the playoffs. And bad players in the regular season remain bad in the playoffs.
Although the Hawks did not play well, the team still won three games in Atlanta, while getting blown out in four games in Boston. How is this possible?
Erich Doerr provided a Monte Carlo simulation of the NCAA tournament. If we look at the results of all 10,000 of his simulations, we see that teams like Davidson, Drake, and Butler were able to win the simulated tournament. In other words, if you played these games enough, odd results can happen.
Of course when we look at all 10,000 simulations, the expected results tend to dominate. Unfortunately, we don’t play these games 10,000 times. We only have one observation. And sometimes that one observation is not very representative of what you would see in a larger simulated sample.
Applying this thinking to the Boston-Atlanta series, I think had Boston and Atlanta played this series over and over again you would see that Boston would tend to dominate. But when you only play once, it is possible for Atlanta to push Boston to seven or even win the series.
And this gets back to a point made in The Wages of Wins. The playoffs are for fun, not for science. This small sample of games does not identify the best team. They do provide us with great entertainment in May and June. And of course, something for sports fans to argue about.
– DJ
Our research on the NBA was summarized HERE.
The Technical Notes at wagesofwins.com provides substantially more information on the published research behind Wins Produced and Win Score
Wins Produced, Win Score, and PAWSmin are also discussed in the following posts:
Simple Models of Player Performance
What Wins Produced Says and What It Does Not Say
Introducing PAWSmin — and a Defense of Box Score Statistics
Finally, A Guide to Evaluating Models contains useful hints on how to interpret and evaluate statistical models.
Wages of Wins Journal 
Evan
May 6, 2008
I’d say that playoff performances like Atlanta’s tend to be hurful rather than helpful for the reasons indicated here: they mislead GMs into making bad personnel decisions.
Two words: Austin Croshere.
antonio
May 6, 2008
What I don’t like is looking at point differential in a playoff series. Point differential is a telling statistic over a period of time, but in a 7 game series it really does not say much. Sample size is simply to small to judge and say the Celtics played great this series or the Hawks played terribly.
Dave
May 6, 2008
You noted that Atlanta’s top 6 were above-average (the equivalent of a 50-win team). Could teams using a shallower rotation in the playoffs contribute to the Hawks outperforming their regular season averages? The top 6 averaged 206.6 minutes per game in the series (as opposed to 205.4 minutes in the regular season) – not much difference. However, in the three Hawks victories, they averaged 216 minutes. It would be interesting to study if factors such as these affect the outcome of playoff series.
Tball
May 7, 2008
Dave’s comment goes to something that was driving me crazy that whole series. Woodson showed he’d bench a player with two fouls for most of the first half. At the start of each game, I was praying Doc would go at Horford (and, after he entered the game, Childress) to try to get them in enough ‘foul trouble’ (are two fouls trouble?) to put them on the bench and make hay with the less productive reserves. This strategy seemed popular in the 80s, but I haven’t seen it employed in quite a while (admittedly, I primarily watch Celtic games).
John
May 7, 2008
Dave’s comment is accurate – one of the stories of the Wages of Wins is about apportioning minutes to players who help you win games.
One of the things the Spurs have been doing for the last five or so years is playing their best players less during the regular season – even in supposedly “big games” they still play their starters according to their normal reduced rotations. Then, in the playoffs, their minutes go up during close games. It’s hard to get Lebron James to play more minutes (he already plays most of them), but it’s easy to get five more minutes from Duncan and Ginobilli – and those five extra minutes can make a big difference.. The Celtics did a similar thing down the stretch with Garnett, and I’ve noticed the Suns started doing something similar with Nash last year.
That’s one of the reasons why every forecast post includes the caveat that it depends on if the minutes are apportioned the way they are expected to be.
Pete
May 7, 2008
Tball wrote:
At the start of each game, I was praying Doc would go at Horford (and, after he entered the game, Childress) to try to get them in enough ‘foul trouble’ (are two fouls trouble?) to put them on the bench and make hay with the less productive reserves
I remember during one of the games feeling dismayed when Marvin Williams went to the bench due to foul trouble and Josh Childress was brought in, thinking how much that likely benefited Atlanta even if their coaching staff didn’t consider it a plus…
yow
May 7, 2008
“But when you only play once, it is possible for Atlanta to push Boston to seven or even win the series”
Atlanta didn’t play Boston ‘once’. They played 7 times. If dberri’s model indicates that Boston is sooo superior to Atlanta, what is the probability of Atlanta winning 3 of 7 games against Boston? Are we expected to believe that an event that’s close to a miracle has happened? Or a more feasible explanation is that Boston is simply not as good as advertised?
Considering that playoffs are probably the only times when all the players are trying their best, I’ll say that Boston is not as good as people think they’re. They just played harder during the regular season than other teams did.
Efficiency differential is just additional information that you can use to judge teams. It would be a monumental mistake to use that solely to judge teams.
Jacob Rosen
May 7, 2008
That would be a very fascinating statistics. I know that there are statistical methods available, in which you can find the probability of a seven-game series occurring based on two team winning percentages.
http://www.diamond-mind.com/articles/playoff.htm
http://www.diamond-mind.com/articles/playoff2002.htm
These might help…
dustin
May 7, 2008
dberri’s model is based off the pythagorean expectation, which I believe has been shown to explain 94% of wins. Also, there is nothing nothing groundbreaking or controversial about the pythagorean expectation in the world of basketball statistics.
The probability of Atlanta taking Boston to 7 games was pretty low, but then again so is the probability of winning the lottery or getting struck by lightning. Low probability != impossible.
“Efficiency differential is just additional information that you can use to judge teams”
This might be true if you have intimate knowledge of basketball and what it takes to win. I would venture, however, that for the majority of the nba fans statistics are probably a better evaluation of team ability. If nba fans were so talented at recognizing what makes a good basketball team, they would be working professionially in a capacity that utilized that skill instead of coming home at 5 or 6 o’clock and turning on the game.
Nash
May 7, 2008
Fans can share their view on the value of different basketball actions / stats by filling out this survey
http://peoplesstatistic.googlepages.com/
yow
May 7, 2008
Average fans will look at the # of regular season wins and who wins the championship in the playoffs. They don’t care about efficiency differentials or wins produced.
Things like these are for gamblers and academics – who are by no means ‘average’ people. These guys want to predict how many games a team will win, who will win when two teams play each other, who is truly better and by how much, etc.
Efficiency differential is a good predictor of how many games a team will win in the regular season. However, just as a team who wins the most regular season games is not necessarily the best team, a team with the best efficiency differential is not necessarily the best team.
The official goal is to win the championship in the playoffs, not to be the best efficiency differential team in the regular season. Therefore, I would argue that the best teams will act accordingly to maximize their chances of winning in the playoffs – i.e., it’s not necessarily in the best interest of teams to go all out during regular seasons and get burnt out by the time they get to the playoffs.
Jason
May 8, 2008
Teams are trying to win championships, not maximize efficiency differential. However, if the latter is a product of playing well, it will come as a result of doing what one does to win a championship. I suspect some teams (like the Spurs over the past few years) do conserve something in the regular season, though I’m not convinced by anecdote that this radically impresses itself as an artificially lower efficiency differential. In the case of the Celtics, I don’t think this explains anything about the series with the Hawks either. Garnett wasn’t used nearly as much in the regular season as he could have been.
In coaching there are a few different strategies that can be employed to maximize success. One method is to emphasize outcome oriented goals (e.g. “this year, we’re going to try to win the championship”). Another is to try to maximize performance and execution (e.g. “we’re going to work our offense, get good shots, and play suffocating defense; we’re not going to lapse; we’re going to outwork them on the boards) and let results follow. This latter strategy tends to bring about a consistency that wins games over the long haul.
tom woods
May 9, 2008
I think a point that you may have left out is the improved performance of Atlanta at home throughout the season. I don’t know if you have wp48 at home for Atlanta, but the only teams in the east to win more games at home than Atlanta this year were the pistons, celtics, and cleveland. Atlanta, Orlando, Toronto, and Washington all won 25 games at home. The difference between Atlanta and the rest of these teams was their performance on the road, where Atlanta only won 12 games.