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We Love Baseball Because of — Not Despite — Lady Luck

With a big game approaching, emotions run high so let’s heed some statistical realities

As we approach the MLB All-Star Game in Los Angeles on July 19, we can be confident of one thing — most current league leaders will not do as well after the break as they did before it. Baseball broadcaster and National Sportswriter of the Year Peter Gammons was among the first to notice this. He wrote in 1989 that, of those baseball players who hit more than 20 home runs before the All-Star break, 90 percent pegged fewer than 20 after the break.

baseball players hitting

Gammons concluded that there was a “second-half power outage,” perhaps because the sluggers got nervous about the possibility of breaking a home run record.

More recently, sports forecaster Max Kaplan made a similar observation, which he called the Home Run Derby Curse. He speculated that league-leading home run hitters do worse after the All-Star break because they alter their swings trying to win the Derby.

The real answer may be simpler: League leaders may just have had more good luck than bad during the first half of the season.

Pick any performance measure — batting average, earned run average, wins above replacement — and most players in the top-10 in any given week, month or season did not do as well the week, month, or season before and will not do as well after. They didn’t temporarily become more skilled; they temporarily became lucky.

Let’s look at MLB’s top 10 hitters, based on OPS — on base plus slugging — during the first and second halves of the 2021 season. One was very unlucky and tore his ACL right before the All-Star game. The other nine all did worse after the break than before it. Their average OPS slumped from 0.969 to 0.806. They didn’t go from great to awful; they went from very lucky to less lucky.

The same is true for the top 10 pitchers, measured by earned run average. One hurt his arm and missed the entire second half of the season. For the rest, their average ERA nearly doubled, from 2.08 to 3.83. One saw his ERA nearly quadruple to 8.18!

This phenomenon, which statisticians call regression to the mean, affects teams as well as individual players. Some teams are above .500 at the All-Star break, some below. After the break, most will perform closer to the mean. The Yankees, for example, aren’t likely to continue their blistering pace, which would extrapolate to 118 wins by the end of the season — more than any team in history. It’s not because the best teams get complacent while the worst teams get energized. The teams with the best records usually have had a second-helping of good luck, while the teams with the worst records usually had more bad luck than good.

In 2021, 18 of 30 teams performed closer to average after the All-Star break; 12 moved farther from average. Some teams flipped, The Mets were 8 games above .500 and in first place in the NL East before the break. They finished the season in third place, 8 games below .500 and out of the playoffs. The Padres were 13 games above .500 before the break, and 4 games below by the end of the season. By contrast, the St. Louis Cardinals were in fourth place in the NL Central, two games below .500 at the All-Star break and finished the season 18 games above .500. The Atlanta Braves were languishing in third place in the NL East, one game below .500 before the break and finished the season in first place, 15 games above .500. They became World Series champions, while the San Francisco Giants, who ended the season with the best record in baseball, got knocked out in their first divisional round.

In any competition where luck plays an important role, the more skilled the competitors, the more the outcome is determined by luck. This is in full display in the post-season. There were nine post-season series in 2021. One was a single-game play-off between the Red Sox and the Yankees who had identical 92–70 regular season records. In the other eight series, the team with the better record in the regular season won four series and lost four. Looking at individual games, the team with the better regular season record won 18 games and lost 18.

So after the All-Star break, two things are likely. Most of the players and teams doing exceptionally well or poorly will now perform closer to the mean. (Take heart, Cincinnati fans.) And, for those teams that make the playoffs, we might as well flip a coin to see who becomes World Series champion. A ground ball could hit a pebble. A pop fly could get lost in the sun. A ball could roll between the first baseman’s legs.

Lady Luck is fickle. That’s why we love the game.


More of Gary Smith’s reflections on the on again–off again romance between Lady Luck and the Hall of Fame:

Why giving the second best guy a chance is a smart move. Business prof Gary Smith explains… People often pay way too much for the first pick, in relation to later performance.

Steph Curry got red hot and torched the “Hot Hand Fallacy” Many statisticians dismiss remarkable streaks like his as the Hot Hand Fallacy. Are they right? Our conclusion is that it is very hard to explain Curry’s 105-shot streak as just another lucky day on the basketball court. He got gloriously red hot.

and

Why did Shane Lowry win the British Open golf championship? Because someone had to. Even among the best golfers, luck is endemic. This is the paradox of luck and skill: the more skilled the competitors are, the more the outcome is determined by luck.


Gary N. Smith

Senior Fellow, Walter Bradley Center for Natural and Artificial Intelligence
Gary N. Smith is the Fletcher Jones Professor of Economics at Pomona College. His research on financial markets statistical reasoning, and artificial intelligence, often involves stock market anomalies, statistical fallacies, and the misuse of data have been widely cited. He is the author of The AI Delusion (Oxford, 2018) and co-author (with Jay Cordes) of The Phantom Pattern (Oxford, 2020) and The 9 Pitfalls of Data Science (Oxford 2019). Pitfalls won the Association of American Publishers 2020 Prose Award for “Popular Science & Popular Mathematics”.

We Love Baseball Because of — Not Despite — Lady Luck