In Major League Baseball’s first half-century, game attendance was entirely determined by teams’ winning percentages, but in recent decades fans have been increasingly attracted by stadium quality, batting performance and outcome uncertainty, raising the importance of competition-enhancing policies such as player free agency, say Seung C.

Ahn of Arizona State University and Young H. Lee of Sogang University in South Korea. When a league policy enhances competitive balance enough to increase doubt about game outcomes and about consecutive-season dominance by 1 standard deviation, attendance increases by 4pc in the American League and 7pc in the National League.

(Source: Journal of Sports Economics)