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 average. The ability of a player to both get on base and to hit for power, two important hitting 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.
The basic formula is
- H = Hits
- BB = Base on balls
- HBP = Times hit by pitch
- AB = At bats
- SF = Sacrifice flies
- TB = Total bases
Although OBP and SLG have different denominators, it is possible to rewrite the expression for OPS using a common denominator. This expression is mathematically identical to the simple sum of OBP and SLG:
Interpretation of OPS 
More expansive sabermetric measurements do attempt to incorporate some or all of the abovementioned factors. Nonetheless, even though it does not include them, OPS correlates quite well with team run scoring.
Other sabermetric stats, such as runs created and Wins Above Replacement, attempt to express a player's contribution directly in terms of runs and/or wins. However, a player's OPS does not have a simple intrinsic meaning.
OPS weighs on-base percentage and slugging average equally. However, on-base percentage correlates better with scoring runs. Statistics such as wOBA build on this distinction using linear weights, avoiding OPS' flaws. Magnifying this fault is that the numerical parts of OPS are not themselves 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.
OPS has the advantage of being based on two already well-established stats whose legitimacy within baseball is uncontroversial. And if those stats are known, it is extremely easy to calculate, as one need only add the two numbers together.
An OPS scale 
|A||Great||.9000 and Higher|
|B||Very Good||.8333 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||Atrocious||.5666 and Lower|
This effectively transforms OPS into a 7 point Likert Scale. Substituting typical Likert scale quality values 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.
On-base plus slugging was first popularized in 1984 by John Thorn and Pete Palmer's book, The Hidden Game of Baseball. 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.
OPS was formerly sometimes known as "Production", for instance 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.
- Babe Ruth, 1.1638
- Ted Williams, 1.1155
- Lou Gehrig, 1.0798
- Barry Bonds, 1.0512
- Jimmie Foxx, 1.0376
- Albert Pujols, 1.0264
- Hank Greenberg, 1.0169
- Rogers Hornsby, 1.0103
- Manny Ramírez, 0.9970
- Mark McGwire, 0.9823
The top four were all left-handed batters. Jimmie Foxx has the highest career OPS for a right-handed batter.
The Top 10 single-season performances in MLB are (all left-handed hitters):
- Barry Bonds, 1.4217 (2004)
- Babe Ruth, 1.3818 (1920)
- Barry Bonds, 1.3807 (2002)
- Barry Bonds, 1.3785 (2001)
- Babe Ruth, 1.3586 (1921)
- Babe Ruth, 1.3089 (1923)
- Ted Williams, 1.2875 (1941)
- Barry Bonds, 1.2778 (2003)
- Babe Ruth, 1.2582 (1927)
- 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 1925, the highest single-season OPS for a right-hander is 1.2224 by Mark McGwire in (1998), which is good for 16th all-time.
Adjusted OPS (OPS+) 
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 formula for OPS+ is
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.
Leaders in OPS+ 
Through May 28, 2012, the career leaders in OPS+ (minimum 3,000 plate appearances, active players in bold) were
1. Babe Ruth, 206
2. Ted Williams, 190
3. Barry Bonds, 181
4. Lou Gehrig, 178
5. Rogers Hornsby, 175
6. Mickey Mantle, 172
7. Dan Brouthers, 170
8. Joe Jackson, 169
9. Ty Cobb, 168
9. Albert Pujols, 168
11. Pete Browning, 163
12. Jimmie Foxx, 163
The only purely right-handed batters to appear on this list are Hornsby, Pujols, and Foxx. Mantle is the only switch-hitter in the group.
The highest single-season performances were:
- Barry Bonds, 268 (2002)
- Barry Bonds, 263 (2004)
- Barry Bonds, 259 (2001)
- Fred Dunlap, 258 (1884) *
- Babe Ruth, 256 (1920)
- Babe Ruth, 239 (1921)
- Babe Ruth, 239 (1923)
- Ted Williams, 235 (1941)
- Ted Williams, 233 (1957)
- Ross Barnes, 231 (1876) **
- 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.
See also 
- See www.baseballprospectus.com or rec.sport.baseball.
- Lewis, Michael. Moneyball: The Art of Winning an Unfair Game, 2003.
- James, Bill. The 96 Families of Hitters. The Bill James Gold Mine, 2009, p.24.
- John Thorn and Pete Palmer, The Hidden Game of Baseball, pp. 69-70.
- Alan Schwarz, The Numbers Game, pp. 165, 233.
- Thorn, John; Pete Palmer (1984). The Hidden Game of Baseball. Doubleday & Company. ISBN 0-385-18283-X.
- Schwarz, Alan (2004). The Numbers Game. Thomas Dunne Books. ISBN 0-312-32222-4.