# Hitting streaks in baseball may be contagious

Teammates of a batter on a streak also hit better than average

Like a popular politician with long “coattails,” a baseball player on a hitting streak seems to lift the performance of those around him. Teammates who play regularly with a streaking player hit at a pace above their own average during those games, a mathematical analysis shows.

“We don’t prove that hitting is contagious,” says study coauthor Joel Bock, an engineer at Scalaton, a software engineering firm in La Mesa, Calif. “But the data show there is something there.”

Streakiness in sports is a controversial topic in science. Some scientists point to a lack of evidence showing that a player can have a true “hot hand” that predicts subsequent success, such as the likelihood that a hot basketball player will make the next shot (SN: 2/12/2011, p. 26). Even less is known about whether a hot hand can extend to others.

Bock and his colleagues analyzed the baseball records of teams on which someone got at least one hit in 30 consecutive games or more. There have been 28 such streaks since 1945, starting with Tommy Holmes’ 37-game tear with the Boston Braves in 1945 and ending with Dan Uggla’s 33-game streak with the Atlanta Braves in 2011.

The researchers found that some players really got hot. In 1969, Willie Davis of the Los Angeles Dodgers had a batting average during a 31-game hitting streak that was 165 points higher than his average for the rest of the year. And Uggla hit a whopping 184 points higher during his streak.

When that same calculation is applied to teammates, it shows that they also hit better – by 11 points on average – during the 28 streaks than during the rest of the year, Bock and his colleagues report December 12 in PLOS ONE. The researchers used only data for those teammates who averaged more than two at-bats per game during each streak.

“The results are plausible,” says economist Jeremy Arkes of the Naval Postgraduate School in Monterey, Calif., who says he was impressed by the 11-point batting average increase.

Arkes says many factors might explain contagious hitting. “There is always the chance that the pitchers have to go around the guy who is hot, and give better balls to hit to those around him,” he says. It’s also possible that by getting on base a lot, a hot hitter distracts a pitcher, increasing the odds that the pitcher will make mistakes and the following batters will get more hits. And some of the effect might result just from having a hot hitter in the clubhouse. “There is extra excitement and extra purpose to playing,” he says.

But other factors might overstate the contagion that Bock and his colleagues suggest, Arkes says: “They are not accounting for the quality of pitching or teams being faced.”

Bock acknowledges being unable to calculate the expertise of opposing pitchers, a diverse cast with many pitchers playing bit parts. He welcomes further examination of the findings. “There is some sort of mechanism going on, but I’m not sure I know what it is,” Bock says.