by Harold Friend

Slugging average is calculated by determining total bases and dividing that number by official times at bat. A hitter slugging 1.000, which has never been achieved over a complete season, would average one base for each official at bat, and advance any runner(s) one base. Slugging average is a valuable measurement, but it can be misleading.

Official Times At Bat vs. Plate Appearances

Barry Bonds set the record for the highest slugging average for a single season when he slugged .863 in 2001. Bonds had 411 total bases in 476 official times at bat, but Barry had 177 walks, 35 intentional walks, 2 sacrifice flies, and was hit by a pitch 9 times, for a total of 699 plate appearances. When Barry batted and hit the ball or struck out, he slugged .863, but for each plate appearance, his slugging average was .588. Of course, it’s inaccurate to NOT count walks and hit by pitch because the batter reaches first, but if there is a runner on second, a runner on third, or runners on second and third, they don’t advance on a walk or hit batsman.

Bonds' Bases On Balls

In 2004, Bonds walked 232 times, was intentionally walked 120 times, had 3 sacrifice flies and was hit 9 times. He reached first base 364 times without hitting the ball. Barry had only 303 total bases but he had only 373 official times at bat for an .812 slugging average. When one adds the 364 times he reached first without making contact, Barry had 737 plate appearances and a .411 slugging average. The opposition didn’t give Bonds the opportunity to make contact because they were better off walking him and taking their chances with the rest of the lineup.

DiMaggio and Cobb Didn't Walk Much

In 1937, Joe DiMaggio had a .673 slugging average, which is 0.139 lower than Barry’s 2004 slugging average of .812, but DiMaggio walked only 64 times in 621 official times at bat. He sacrificed twice, was hit 5 times, and had 418 total bases, or 115 more than Barry. In 692 plate appearances, DiMaggio’s slugging average becomes .604. This means that every time the 1937 Joe DiMaggio batted (.604), compared to every time the 2004 Barry Bonds batted (.411), DiMaggio was a more productive slugger because opposing managers in 1937 chose to allow DiMaggio to swing, while opposing managers in 2004 chose to pitch around Barry, who would not chase too many balls.

An extreme case is Ty Cobb in 1911. Baseball’s greatest player, with the possible exception of Babe Ruth, hit .420 with a .621 slugging average and 367 total bases in 591 official times at bat, but Cobb walked only 44 times. Using plate appearances, Cobb’s .621 slugging average drops only 0.060 points to .561.


At least two conclusions can be reached. Managers can lessen the threat presented by great sluggers, especially home run sluggers by not pitching to them, which is not news, and a hitter’s slugging average provides a batter’s effectiveness only when he makes contact. When Barry batted in 2004, his .812 slugging average could be misleading because there was almost a 50 percent chance he would NOT hit the ball. DiMaggio’s .673 and Cobb’s .621 provide better pictures because they made contact most of time. An interesting investigation would be to analyze the effectiveness of sluggers waiting out walks.


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