Studying baseball’s offensive surge

LINCOLN, Neb. – It’s not the “juiced ball,” it’s not cozy ballparks and it’s not expansion that caused the explosion of offense in Major League Baseball in the 1990s.

Rather, the root causes are a new, free-swinging hitting style, combined with a new relationship between hitters and pitchers, lighter bats and stronger players, two University of Nebraska-Lincoln historians report in a soon-to-be published paper, “Baseball’s Great Hitting Barrage of the 1990s.”

Ben Rader and Ken Winkle, like millions of other baseball fans, watched in fascination as baseball offenses exploded, starting in 1993, when major-league batting averages jumped 10 points and runs per game increased from 8.6 to 9.2 compared to 1992.

And that was just the beginning. In the first six seasons of the three-divisional era (1994-99), the major leagues’ composite batting average was .281, up from .257 in the two-divisional era (1969-93), while runs per 100 at bats increased from 12.4 to 14.3.

Home run barrage.

Home runs were at the center of the barrage, with home runs per 100 at bats increasing by more than one-third, from 2.3 in the two-divisional era to 3.1 in the three-divisional era.

Rader and Winkle started looking for the underlying causes of the revolution when Rader began work on a 1990s chapter for a revised version of his acclaimed 1992 book, “Baseball: A History of America’s Game.”

As their research progressed, one factor came to stand out.

“Across the board, the biggest answer we found was the changing strike zone and the relationship of batters to pitchers,” Rader said.

“This is hard to measure statistically, but the area of the strike zone has moved away from the batters, away from the inside of the plate to the outer side of the plate, and the high strike, essentially a pitch above the belt, has been taken away.

“Also, pitchers don’t have as much freedom to throw inside as they used to. There seems to be a new convention and the umpires enforce this convention.

“You can’t just throw the old ‘brush-back’ pitch, where a Bob Gibson wouldn’t let a hitter dig in. Some pitchers the last couple of years have tried to reclaim it, but when Pedro Martinez of the Boston Red Sox started throwing inside and high, Frank Robinson suspended him.”

Lighter bats.

Rader and Winkle concluded that lighter bats and stronger players were also probable contributing factors.

The average weight of a major-league bat dropped from 33 ounces in 1991 to 31 ounces in 1996, they reported, allowing hitters to wait longer on pitches and produce greater bat speed when they swing.

While the average height and weight of major-league players was virtually identical in 1990 and 1998, they speculated that today’s players are indeed stronger thanks to year-round training regimens, more careful attention to diet and (possibly) to the alleged use of illegal steroids.

“I contacted the strength coaches at all of these places and they claim they don’t have any systematic data on whether players are getting stronger or not,” Rader said.

“Maybe they just don’t want the competition to know how strong their players are, but we couldn’t get any data.”

Rejected theories.

In rejecting the popular juiced-ball theory, the historians cited scientific studies of baseballs, an inspection by major league executives and newspaper reporters of the Rawlings manufacturing and testing facilities, and the improbability that all of the thousands of individuals involved in manufacturing baseballs would keep quiet about a conspiracy to change the ball.

The cozy ballpark theory was undermined when they found that the dimensions of major league ballparks remained virtually unchanged from 1990 to 1998.

They disposed of the diluted-pitching theory when they found no correlation between expansion and increased offensive output.

MLB strikes back.

Major League Baseball, ostensibly in an effort to speed up the game, tried to retrain its umpires to call the rule-book strike zone this spring, with predictable howls from hitters.

Whether the “new” strike zone will bring back some offensive-defensive balance remains to be seen.

“It will be fascinating to see what kind of results they’ll have,” Rader said.