Newfangled Stats: What is OPS in Baseball (and other information)?

I grew up collecting baseball cards. Mind you, this was at the height of the junk wax era (e.g., 1991 Donruss or 90’s era Pinnacle). But that didn’t matter to me then or now. The cards were a way for me to hold in my hand the game I enjoyed playing and watching.

Many days were spent looking at the back of the cards, reviewing and memorizing statistics. Simple, easy-to-understand stats: batting average, RBI, home runs, strikeouts, ERA.

OPS somehow didn’t make the cut for 1991 Donruss, or most (maybe all?) card companies. Younger me would have had no idea that OPS is actually fairly straightforward.

So, what is OPS?

OPS is a measurement of player’s ability to both hit for power and get on base. To calculate OPS, add a player’s on-base percentage to their slugging percentage.

If you are familiar with those statistics, you may realize they cannot mathematically be added so quickly due to having different denominators. But that doesn’t stop anyone from doing it, and at this point it is a fairly common way for people to quickly understand how well a player both gets on base and hits for power.

But going back to those 90s era baseball cards. Why was OPS omitted from their backs? I call OPS a newfangled stat in the title, but it’s not really all that new.

When was the OPS stat created?

Pete Palmer created the OPS stat some time before 1978, but the Dodgers under Branch Rickey were using a statistic close to OPS as early as 1954. The OPS statistic began gaining traction after Pete Palmer and John Thorn published their book The Hidden Game of Baseball in 1984, but even in a 2000 St Petersburg Times article, the stat is still being talked as not being universally embraced in baseball: “[the OPS] statistic is in vogue among the younger general managers and is catching on with the mainstream media”.

So, how is OPS viewed today in 2021?

Opinions on OPS

OPS was being described as “in vogue” in the early 2000’s, but now it is widely accepted across baseball and media outlets. However, that doesn’t make it necessarily a quality stat to use.

According to Fangraphs, OPS has a flaw: it weights on-base percentage (OBP) and slugging percentage (SLG) equally. But, that’s not actually true.

On-base percentage has a 1.8x more effect on run scoring than slugging percentage. So, OPS does not necessarily present an accurate picture of a player’s impact on run scoring (which many sabermetricians argue is how player’s offensive impact should be measured by).

So, should you use the statistic?

That depends. I like to think I’m current on baseball player evaluation (understanding at a fundamental level to help me in my fantasy baseball leagues, not at a professional or deep analytical level). I use OPS in conjunction with other metrics.

However, if I am speaking to friends who more casually follow baseball I don’t try to expand the statistical conversation past OPS. I have found that OPS is a good upper threshold in those conversations for helping someone gain a more holistic understanding of a player’s contribution that exceeds batting average and home runs.

Explaining the difference in player quality can be as straightforward as just highlighting players with high OBP or SLG and comparing with the players with high OPS. Check the next section for a breakdown.

Who are the Players with High OPS? (2019 Season Example)

To give you an idea of which players sit atop the OPS leaderboard, here is a look at the 2019 leaders I compiled:

Exactly the players you would expect. Each of these guys have an OPS over 1.000. If you start looking at players with the highest OBP, you start to see why OPS can be helpful to consider along with OBP.

Both Luis Arraez and Matt Joyce were in the top 10 for OBP in 2019, but each had below a .900 OPS (i.e., low slugging percentage).

Let’s take a look at the average OPS for 2019.

What is the average OPS for major league baseball players?

Taking a one-year sample (2019), the average OPS for a major league baseball player is .758. Christian Yelich, the league leader for OPS in 2019, had a 45% higher OPS (1.100).

Players right around the league average were:

Highest Career OPS

To further put into perspective how great the 2019 season was for those players with over 1.000 OPS, only 8 players have achieved that for their career:

If you’re looking for a list of some of the best baseball players, then this is not a bad place to start. But is it possible that some of the players benefited from their home ball park? Or from the era they played in?

I can’t tell that from just looking at the players or their stats, but that is where OPS+ comes in.

How are OPS and OPS+ different?

To answer that question, let’s start by looking at the top 10 OPS leaders and their OPS+. Note: this does not include players who played only in the Negro Leagues.

The players with the highest career OPS still show up near the top of OPS+ rankings, but I notice some movement, particularly with Foxx and Greenberg shifting down; it may be coincidence, but both players played during the 1930’s and through the mid 1940’s.

But what does the OPS+ tell us?

What is OPS+ and How Does it Compare to OPS?

From MLB’s website:

OPS+ takes a player’s on-base plus slugging percentage and normalizes the number across the entire league. It accounts for external factors like ballparks. It then adjusts so a score of 100 is league average, and 150 is 50 percent better than the league average.

In other words, OPS+ attempts to put everyone on equal footing. No Coors Park inflating stats. No dead ball era, or likewise no HR-happy ball either. It looks how well each player performs in OPS relative to their peers at the time.

I hope you love normalization as much as I do.