Baseball's Great Hitting Barrage of the 1990s

In the 1990s, an impressive body of evidence pointed in the same direction. In that decade, baseball entered a new era; it had become a new game. ¹ Consider the following.

A player strike in 1994-95 resulted in not only two mangled seasons but, for the first time since 1904, the cancellation of a World Series (1994).

Following the example of professional football, Major League Baseball provided for a wild-card team to compete in the divisional championship series of each league (1994) and experimented for the first time in its history with interleague play (1997).

In the 1990s, Major League Baseball witnessed a "Latino invasion"; by the end of the decade, more than 20 percent of all big leaguers hailed from Central America, the Caribbean Basin, or Mexico.

Reflected in Ken Burns's widely acclaimed documentary Baseball: An American Epic (1994) and a series of popular movies, such as Bull Durham (1988), a mass nostalgia for the "old game"--the game as it once was--swept across the country. Seeking to cash in on the urge to reconnect to the past and to maximize revenues from concessions and corporate purchasers of tickets, the clubs rushed to build new "retroparks" that resembled in some respects the ball fields built early in the twentieth century.

And, finally, there was the great offensive barrage. In the 1998 and 1999 seasons, the soaring home run totals of Mark McGwire and Sammy Sosa suddenly crashed through (with plenty of room to spare) earlier seasonal barriers established by Babe Ruth and Roger Maris.

This paper focuses on only one aspect of the new game--the hitting barrage of the 1990s. ² We begin by trying to establish statistically the existence of the hitting barrage. We ask in precisely what respect and when was there a significant increase in hitting. Since, as every fan of the game knows, baseball is rich in statistics, answering this question is relatively simple.

Second, we attempt to identify and assess the relative importance of the key determinants of offensive productivity in the 1990s. To the extent permitted by available data, we employ statistical analysis to examine several popular explanations for the increased productivity. At the same time, we recognize that statistics are useless in explaining some of the key determinants of increased offensive productivity. In particular, we conclude that a new style of hitting occasioned by changes in the de facto shape and size of the strike zone and the relative freedom of pitchers to move hitters back from the plate is an important reason for the modern hitting revolution.

Was There A Hitting Revolution In The 1990s?

During the two-divisional era (1969-93), the overall offensive output of the big leagues never fully recovered from the great drought of the 1960s. Lowering the pitching mound in 1969, an apparent reduction in the size of the de facto strike zone (the zone called by the umpires rather than the one provided for in the rules) in the same season, and the American League's adoption of the designated hitter in 1973 did lead to slight improvements in hitting. But both runs and home runs per game remained well below the marks achieved in the 1921-60 era. Indeed, during the two-divisional era's twenty-five seasons, nearly half the league leaders in home runs failed to scale the modest plateau of 40, and only two players--George Foster, with 52 in 1977, and Cecil Fielder, with 51 in 1990--managed to hit more than 50 homers in a single season.

With a suddenness reminiscent of the 1920 and 1921 seasons, the 1993 and 1994 seasons signaled a breakthrough in offensive productivity (see Table 1). An omen of the great reversal in hitting arrived with the 1987 season; during that exceptionally hot summer, the sluggers banged out...