The San Diego Padres spent the past month fighting off their instate rivals atop the NL West, and the Tampa Bay Rays have battled the New York Yankees all season in the AL East. If only a few more of their fans had actually attended their games, these two might actually have some breathing room.

Fans are surrounded by empty seats throughout Wrigley Field as they watch a game between the Pittsburgh Pirates and the Chicago Cubs on September 1. Getty Images

Neither team is filling more than 65% of its seats this season despite playing well, and a new study says this could already have cost them several wins apiece. Erin Smith, a Ph.D. candidate at NYU's Stern School of Business, co-wrote a paper that shows a 48% increase in a team's attendance makes that team score an extra run every game. Before Monday's games, this scoring boost would have bumped the Padres to a game ahead of the San Francisco Giants instead of being tied with them, and it would have put the Rays two games ahead of the Yankees instead of a half-game behind. In the NL East, the Atlanta Braves would have leapfrogged the Philadelphia Philles.

Ms. Smith's study, which was published this year in the Journal of Quantitative Analysis in Sports, used a regression model to account for things like team ability, stadium size and weather. By doing this, she showed that increased attendance does, in fact, help teams play well, instead of this simply being a matter of good teams drawing more fans.

Studies like these will almost certainly convince San Diegans to leave the beach and spend their free time in the ballpark.

Attendance Boost Here's how many additional wins some of baseball's contending teams would have if they had 100% attendance in every home game this season. DivisionTeamAdditional WinsDivisionTeamAdditional WinsAL EastYankees0.79NL EastPhillies0AL EastRays4.06NL EastBraves2.89AL CentralTwins0NL CentralReds3.18AL CentralWhite Sox2.52NL CentralCardinals0.79AL WestRangers3.04NL WestPadres3.41AL WestAthletics6.05NL WestGiants0.72 AL EastYankees0.79NL EastPhillies0AL EastRays4.06NL EastBraves2.89AL CentralTwins0NL CentralReds3.18AL CentralWhite Sox2.52NL CentralCardinals0.79AL WestRangers3.04NL WestPadres3.41AL WestAthletics6.05NL WestGiants0.72

—David Biderman