# On-base plus slugging

On-base plus slugging (OPS) is a sabermetric baseball statistic calculated as the sum of a player's on-base percentage and slugging percentage.[1] The ability of a player both to get on base and to hit for power, two important offensive skills, are represented. An OPS of .900 or higher in Major League Baseball puts the player in the upper echelon of hitters. Typically, the league leader in OPS will score near, and sometimes above, the 1.000 mark.

## Equation

The basic equation is

${\displaystyle OPS=OBP+SLG\,}$

where OBP is on-base percentage and SLG is slugging average. These averages are defined.

${\displaystyle OBP={\frac {H+BB+HBP}{AB+BB+SF+HBP}}}$

and

${\displaystyle SLG={\frac {TB}{AB}}}$

where:

In one equation, OPS can be represented as:

${\displaystyle OPS={\frac {AB*(H+BB+HBP)+TB*(AB+BB+SF+HBP)}{AB*(AB+BB+SF+HBP)}}}$

## History

On-base plus slugging was first popularized in 1984 by John Thorn and Pete Palmer's book, The Hidden Game of Baseball.[2] The New York Times then began carrying the leaders in this statistic in its weekly "By the Numbers" box, a feature that continued for four years. Baseball journalist Peter Gammons used and evangelized the statistic, and other writers and broadcasters picked it up. The popularity of OPS gradually spread, and by 2004 it began appearing on Topps baseball cards.[3]

OPS was formerly sometimes known as "Production." For instance, "Production" was included in early versions of Thorn's Total Baseball encyclopedia, and in the Strat-O-Matic computer baseball game. This term has fallen out of use.

OPS gained in popularity because team average OPS correlates well with team runs scored. However, it is not mathematically legitimate to use this correlation to assume that individual OPS correlates as well with individual runs created, nor is it legitimate to assume that individual OBP (On Base Percentage) correlates well with individual runs created. Unfortunately, there is no simple way to measure individual runs created.[citation needed]

## An OPS scale

Bill James, in his essay titled "The 96 Families of Hitters"[4] uses seven different categories for classification by OPS:

Category Classification OPS Range
A Great .9000 and Higher
B Very Good .8334 to .8999
C Above Average .7667 to .8333
D Average .7000 to .7666
E Below Average .6334 to .6999
F Poor .5667 to .6333
G Very Poor .5666 and Lower

This effectively transforms OPS into a 7-point ordinal scale. Substituting quality labels such as Excellent (A), Very Good (B), Good (C), Average (D), Fair (E), Poor (F) and Very Poor (G) for the A–G categories creates a subjective reference for OPS values.

The top ten Major League Baseball players in lifetime OPS, with at least 3,000 plate appearances through the end of the 2018 season were:

1. Babe Ruth, 1.1636
2. Ted Williams, 1.1155
3. Lou Gehrig, 1.0798
4. Barry Bonds, 1.0512
5. Jimmie Foxx, 1.0376
6. Hank Greenberg, 1.0169
7. Rogers Hornsby, 1.0103
8. Mike Trout, 1.000
9. Manny Ramirez, 0.9960
10. Mark McGwire, 0.9823

The top four were all left-handed batters. Jimmie Foxx has the highest career OPS for a right-handed batter.[5]

The top ten single-season performances in MLB are (all left-handed hitters):

1. Barry Bonds, 1.4217 (2004)
2. Barry Bonds, 1.3807 (2002)
3. Babe Ruth, 1.3791 (1920)
4. Barry Bonds, 1.3785 (2001)
5. Babe Ruth, 1.3586 (1921)
6. Babe Ruth, 1.3089 (1923)
7. Ted Williams, 1.2875 (1941)
8. Barry Bonds, 1.2778 (2003)
9. Babe Ruth, 1.2582 (1927)
10. Ted Williams, 1.2566 (1957)

The highest single-season mark for a right-handed hitter was 1.2449 by Rogers Hornsby in 1925, 13th on the all-time list. Since 1935, the highest single-season OPS for a right-hander is 1.2224 by Mark McGwire in 1998, which was 16th all time.[6]

OPS+, Adjusted OPS, is a closely related statistic. OPS+ is OPS adjusted for the park and the league in which the player played, but not for fielding position. An OPS+ of 100 is defined to be the league average. An OPS+ of 150 or more is excellent and 125 very good, while an OPS+ of 75 or below is poor.

The basic equation for OPS+ is

${\displaystyle OPS+=100*({\frac {OBP}{*lgOBP}}+{\frac {SLG}{*lgSLG}}-1)}$

where *lgOBP is the park adjusted OBP of the league (not counting pitchers hitting) and *lgSLG is the park adjusted SLG of the league.

A common misconception is that OPS+ closely matches the ratio of a player's OPS to that of the league. In fact, due to the additive nature of the two components in OPS+, a player with an OBP and SLG both 50% better than league average in those metrics will have an OPS+ of 200 (twice the league average OPS+) while still having an OPS that is only 50% better than the average OPS of the league. It would be a better (although not exact) approximation to say that a player with an OPS+ of 150 produces 50% more runs, in a given set of plate appearances, as a player with an OPS+ of 100 (though see clarification above, under "History").

Through the end of the 2018 season, the career top twenty leaders in OPS+ (minimum 3,000 plate appearances) were:[7]

The only purely right-handed batters to appear on this list are Hornsby, Foxx, Trout, McGwire, and Thomas. Mantle is the only switch-hitter in the group.

The highest single-season performances were:[8]

1. Barry Bonds, 268 (2002)
2. Barry Bonds, 263 (2004)
3. Barry Bonds, 259 (2001)
4. Fred Dunlap, 258 (1884) *
5. Babe Ruth, 256 (1920)
6. Babe Ruth, 239 (1921)
7. Babe Ruth, 239 (1923)
8. Ted Williams, 235 (1941)
9. Ted Williams, 233 (1957)
10. Ross Barnes, 231 (1876) **
11. Barry Bonds, 231 (2003)

* - Fred Dunlap's historic 1884 season came in the Union Association, which some baseball experts consider not to be a true major league.

** - Ross Barnes may have been aided by a rule that made a bunt fair if it first rolled in fair territory. He did not play nearly so well when this rule was removed, although injuries may have been mostly to blame, as his fielding statistics similarly declined.

If Dunlap's and Barnes' seasons were to be eliminated from the list, two other Ruth seasons (1926 and 1927) would be on the list. This would also eliminate the only right-handed batter in the list, Barnes.

## Criticism

Despite its simple calculation, OPS is a controversial measurement. OPS weighs on-base percentage and slugging percentage equally. However, on-base percentage correlates better with scoring runs.[9] Statistics such as wOBA build on this distinction using linear weights. Additionally, the components of OPS are not typically equal (league-average slugging percentages are usually 75–100 points higher than league-average on-base percentages). As a point of reference, the OPS for all of Major League Baseball in 2008 was .749.[10]

## Notes

1. ^
2. ^ John Thorn and Pete Palmer, The Hidden Game of Baseball, pp. 69-70.
3. ^ Alan Schwarz, The Numbers Game, pp. 165, 233.
4. ^ James, Bill. The 96 Families of Hitters. The Bill James Gold Mine, 2009, p.24.
5. ^ "Career Leaders & Records for OPS". Baseball-Reference.com. Retrieved July 26, 2019.
6. ^ "Single-Season Records for OPS". Baseball-Reference.com. Retrieved July 26, 2019.
7. ^ "Career Leaders & Records for Adjusted OPS+". Baseball-Reference.com. Retrieved July 26, 2019.
8. ^ "Single-Season Leaders & Records for Adjusted OPS+". Baseball-Reference.com. Retrieved July 26, 2019.
9. ^ Lewis, Michael (203). Moneyball: The Art of Winning an Unfair Game[page needed]
10. ^ "2008 Major League Baseball Standard Batting". Baseball-Reference.com.