What is OPS in Baseball?
OPS in baseball is arguably the first “advanced stat” that sports fans come across. While traditional stats like batting average and ERA count how many times something happens, advanced stats combine data in more interesting ways. Sometimes advanced stats fail because they are impossible to interpret.
Unlike other advanced stats, OPS is very easy to motivate, understand, and analyze. Some players hit for power while some hit for average. Both are important and the best hitters do both – OPS measures this.
In this article, we’ll look at OPS from every angle. We’ll help you understand the stat on multiple levels. How is OPS computed, what is a good OPS, and what alternatives are there? You can use the table of contents below to skip ahead to different sections.
I highly recommend reading the section “comparison to other advanced stats” below to help understand how different stats can be viewed. There is always a tradeoff between interpretability and accuracy when defining metrics and I think OPS does a very good job of being simultaneously accurate and interpretable. This is why OPS in baseball is such a commonly used stat when talking about how good hitters are.
What is OPS?
In the introduction we touched on why OPS in baseball is such an intuitive statistic. To be a good hitter you need to hit often and for power. Batting average only counts how often a player gets a hit and on-base percentage counts how often they get on base. This is only half the formula to being a good hitter.
Slugging percentage is all about measuring power. It counts how many bases a player gets per at bat. This means home runs are worth more than triples and doubles are worth more than singles.
The way that OPS is calculated is in the name. OPS stands for on base plus slugging. It is computed by adding a player’s on base percentage (OBP) to their slugging percentage (SLG). Symbolically, OPS = OBP + SLG .
The main difference between slugging percentage and OPS is that on base plus slugging places more values on singles and doubles than slugging percentage does. In slugging percentage, a home run is worth 4 times as much as a single. In OPS, it is only worth 2.5 times as much. Check out the graphic below to see how each type of hit contributes to OPS in baseball.
If we convert on base percentage and slugging percentage into their constituents – singles, doubles, etc. – then we can create a different, equally accurate formula for OPS. On base plug slugging can also be computed:
OPS = (2\cdot(BB+HBP+1B)+3\cdot2B+4\cdot 3B+5\cdot HR)/AB .
What is a Good OPS in Baseball
Over the last few years, the league average on base plus slugging has ranged from as low as 0.700 to about 0.750. The best players in the league often do much better though. The league leaders usually have an OPS anywhere from 0.950 to as high as 1.1. In Barry Bonds famous 2004 season, he put up a 1.4 OPS. To understand why this is so impressive, if you got a single 66% of the time, a double 34% of the time, and never got out, Barry Bonds still had a better season than you.
The table below shows the top 5 OPS numbers in the 2022 and 2010 seasons.
Rank | 2022 | 2010 |
---|---|---|
1 | Judge, 1.111 | Hamilton, 1.044 |
2 | Alvarez, 1.019 | Cabrera, 1.042 |
3 | Trout, .999 | Votto, 1.024 |
4 | Goldschmidt, .981 | Pujols, 1.011 |
5 | Altuve, .921 | Bautista, .995 |
As you can see, the high .900s typically puts you among the elite players in the league. Break 1 in OPS and you have a good chance at being considered one of the best hitters in baseball.
The table below shows the top 5 players in career OPS before the start of the 2023 season.
Rank | Player | Rank |
---|---|---|
1 | Babe Ruth | 1.164 |
2 | Ted Williams | 1.116 |
3 | Lou Gehrig | 1.080 |
4 | Oscar Charleston | 1.064 |
5 | Barry Bonds | 1.051 |
OPS is a Rate Stat
One interesting thing to note from the video at the end of the last section is that oftentimes players rank very highly at the beginning of their careers and fall down the list as time passes. This is because OPS in baseball is a rate stat.
Rate statistics are those which are averages or measured as “successes per attempts”. OPS basically counts 1 plus the number of bases per at bat. Therefore, OPS in baseball is a rate stat. In addition to rate stats, there are also things called “counting stats”. Counting stats count how many times something happened.
One of the main differences between rate stats and counting stats is that career rate stats typically decrease as a player gets older. This is because the player’s are less efficient in their old age and so their career averages decrease.
This is why a guy like Aaron Judge might be in the top 20 all-time in OPS right now but probably shouldn’t be considered a top 20 all time player. He is in his prime so his OPS looks better when compared to guys who played full careers.
Shortcomings of On Base Plus Slugging
OPS tries to fix the problems associated with the more basic stats OBP and SLG. The problem, though, is that OPS doesn’t really fix the problem it set out to fix! It is better than either OBP or SLG, but it isn’t the best we can do. Let me explain.
Trying to measure how good a hitter is is complicated. This is because there are multiple possible outcomes from an at bat. A double is better than a single, a homer is better than a double. It isn’t as simple as measuring “success/failure” in an at bat.
Batting average and on base percentage measure how good a hitter is by just counting successes/failures. It is a good first attempt, but doesn’t accurately reward players who more often have better outcomes.
Slugging percentage tries to fix this by counting the number of bases someone gets per at bat. This means that a player who hits proportionally more home runs will be seen as the better player. This tries to fix the problem from the last paragraph but introduces a new problem. A home run is worth the same as four singles. However, I would rather have four straight singles than a home run followed by three outs.
It is difficult to measure the relative value of various events in baseball; OPS tries to do this.
Slugging percentage doesn’t accurately measure the relative value of the possible outcomes of an at bat. It places too much value on triples and home runs. OBP, conversely, doesn’t place enough value on doubles, triples, and home runs. Adding the two (resulting in OPS) should average this effect out and more accurately place value on various outcomes.
And it does. But it doesn’t do it perfectly. For example, a single is indisputably more valuable than a walk. OPS rates them the same. While OPS does better than OBP and better than SLG at measuring the relative value of every outcome, it still falls short.
Comparison to Other Advanced Stats
The problem with OPS is that it doesn’t perfectly measure the difference in value between walks, singles, doubles, triples, and home runs. The stats wRAA and wOBA do. On the other hand, while OPS is relatively easy to understand, wRAA and wOBA are not. Every stat has to balance interpretability with accuracy. The following graphic summarizes the various stats we’ve considered in this article on a very, very important spectrum.
A stat that makes no sense to general audiences has no value. On the other hand, a stat that doesn’t accurately measure player quality is also useless. All the stats on the above spectrum trade off these two considerations with various weight on each factor. I actually think wOBA and wRAA are relatively easy to interpret, and I’ve written about wOBA and wRAA here to help you understand. Let me summarize.
The problem with slugging percentage and on base plus slugging is that they don’t perfectly measure the relative value of different outcomes of an at bat. They arbitrarily assign the value of home runs as either four times (SLG) or 2.5 times (OPS) as valuable as singles. wRAA figures out the precise relative value of different types of hits (the answer is closer to 2.35x).
wRAA uses historical data to determine how valuable a single, double, triple, walk, and home run are relative to one another. To do this, it uses the run expectancy matrix to value each of these events and therefore nearly perfectly measures how good a hitter is. To read about the run expectancy matrix and RE24, check out this article.
A second interesting alternative to OPS is OPS+. This stat uses players’ raw OPS numbers, but adjusts them for the ballpark (some stadiums allow more home runs and doubles than others) and for the league average.
This is, in general, a good thing to do. However, OPS+ is more difficult to interpret than OPS because it is “normalized”. My opinion is if you’re going to move down the interpretability spectrum, you better move up the accuracy spectrum. For this reason, I think wRAA is a much better stat than OPS+.
Final thoughts
OPS is arguably the most commonly used stat by true baseball fans when discussing how good a hitter is. It is a good stat because it is very easy to understand while simultaneously accurately measuring player quality. It is the first statistic I would recommend for baseball enthusiasts to understand and the first stat I would use in any discussion about how good a player is. Overall, on base plus slugging is a very well designed stat.
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