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While watching a New York Mets game early this season, before one plate appearance the broadcast graphics displayed that catcher John Buck had a batting average (AVG) of .400 and an on-base percentage (OBP) of .396. Several games later I saw a similar phenomenon for Buck, whose OBP was again several points lower than his AVG. (In other words, the stats presented were very likely to be actual and not an on-screen typo.)

How is this possible? By my understanding, the two are calculated as follows:

AVG = (hits) / (at-bats)

and

OBP = (times reaching first base) / (plate appearances)

It would seem to me that the conditions by which a plate appearance does not count as an at-bat would always result in the batter reaching first.

What could have happened to cause Buck's on-base percentage to drop below his average?

1 Answer 1

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Sacrifice Flies

It can happen because Sacrifice Flies are in the denominator of the on-base percentage

OBP=(H+BB+HBP)/(AB+BB+HBP+SF),

but not in the batting average

AVG=H/AB.

For small numbers of at-bats, it is possible (though unlikely) for a player's on-base percentage to be lower than his batting average (H/AB). This happens when a player has almost no walks or times hit by pitch, with a higher number of sacrifice flies (e.g. if a player has 2 hits in 6 at-bats plus a sacrifice fly, his batting average would be .333, but his on-base percentage would be .286). The player who experienced this phenomenon with the most number of at-bats over a full season was Ernie Bowman. In 1963, with over 125 at-bats, Bowman had a batting average of .184 and an on-base percentage of .181.

Source

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  • That makes perfect sense; a sac fly shouldn't count against you for batting average, but since you didn't actually get on-base, it wouldn't count favorably towards OBP. Oct 14, 2013 at 12:55

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