Introduction
A movie about statistics, return on investments, and market inefficiencies does not sound like a hit movie to most. However, a movie with a box office of over a hundred million dollars, multiple Oscar nominations and numerous awards won does. This is Moneyball, a movie that tells the story of how the Oakland Athletics, led by general manager Billy Beane, used the above and more to achieve glory.
The story
This movie tells the story of Billy Beane, the general manager of the professional baseball team Oakland Athletics. After a disappointing 2001 run, the departure of 3 key players and a limited budget, Billy needs to find a way to create a competitive team. In his search for the right strategy, he stumbles upon Yale graduate Peter Brand, a young man with new and radical ideas that would change the scouting approach forever.
Using the so called sabermetric method, they evaluated players and hence went on a search for undervalued players for the team. Players who were underestimated by the big teams because of biased reasons such as appearance, personality and age were made affordable for the low-budget team of the Oakland Athletics.
After a disappointing start, the team encounters internal problems, with very little support for this strategy and the head coach being fired by Billy Beane. However, after some time the team starts to run and ends up winning the American League West and wins 20 matches in a row and in so breaking this record. They eventually lose in the American League Division Series, where in the movie a non-disclosed analyst explains that not all can be quantified. After this, the strategy is implanted by the Red Sox who subsequently win two world series.
Real story VS movie
As stated this movie is based on a real-life story, however there are some differences between the movie and reality. For once, the internal conflict in the movie was severely exaggerated as in real life most of the staff agreed upon Beane’s new approach of scouting. In the movie, Billy was constantly fighting the scouts and other staff, while in real life, most were in line with him and his strategy.
The other big difference is the lack of acknowledgment to the strengths of the “old-approach players”. Even though the sabermetric method made the Oakland Athletics trade multiple players who turned out to be important for their season, multiple key players in that 2002 season were already there when the approach was implemented.
The sabermetric method
Something that was well shown in the movie was the use of the sabermetric method. This is a quantitative way to value baseball players on their on-pitch performances. By using statistical analysis, the Oakland A’s found out that the two most important statistics in a player were their slugging percentage and on-base percentage.
The slugging percentage (SLG) is given as follows:
SLG = 1B + 2*2B + 3*3B + 4*HRAB
With:
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1B = Number of singles;
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2B = Number of doubles;
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3B = Number of triples;
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HR = Number of homeruns;
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AB = Number of at-bats, also known as time at bat.
In words, the slugging percentage is the amount of bases someone gets on average per time at bat. They found that the SLG of a player was a key indicator of the importance of a player for a team. Another key-indicator they found was the on-base percentage (OBP). This is simply defined as how frequently a batter reaches base. In a mathematical definition, it is given by:
OBP = H + BB + HBPAB + BB + HBP + SF
With:
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H = number of hits;
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BB = number of Base on Balls, also known as walks;
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HBP = Numbers of hit by pitches;
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AB = Number of at-bats, also known as time at bat;
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SF = Sacrifice flies.
With these two statistics Billy answered the simple questions whether someone can hit and whether someone can run. In the past, scouts based their opinions on the following strengths: speed, quickness, arm strength, hitting ability and mental toughness. Players would get a rating per strength and based upon that, scouted or not. Hence, by implying these new tools they quantified the scouting and management processes in baseball.
Post Moneyball
Over time the tools and indicators used in the sabermetric method have evolved a lot. So much even, that it is too much to go fully into in this article, as that deserves its own article. However one can imagine that with more and more information being available, the preciseness of the estimation of the value per player has increased a lot. In the last couple of years machine learning has taken a more prominent role in determining the proper value of a player and it being less based on flair and personality.
What we can conclude from this story
Even though the movie is not entirely truthful, there are certainly some key takeaways about
statistics in there.
Firstly, statistics can be used in almost any branch, be it baseball in this case, but there are lots of examples where statistics are used in non-conventional ways. This means that for us as statisticians there are a lot of non-conventional ways in which we can use our studies and bring new insights.
Another key point is to not linger in the past. As stated in this article, lots of teams could have gotten this insight before the Oakland A’s, but they lingered too long in the old idea that a player should be bought based on only the home-runs and five strengths stated above. This is also the other way around, as nowadays the sabermetric method has evolved and certain tools that were seen as key indicators by Billy and Peter in the movie are not used anymore. Over time, the tools and indicators used in the sabermetric method have evolved significantly. This shows that all statisticians should keep looking for better and new indicators to observe value. Because before you know it, some small budget baseball team comes in with new insights and takes the win.