In this post, I’ll explain a few statistics developed in recent years that perhaps do the best job of relaying offensive production by valuing what actually creates runs: Weighted On Base Average (wOBA), Weighted Runs Created (wRC) and Weighted Runs Created Plus (wRC+).
Weighted On Base Average (wOBA)
Developed by Tom Tango in The Book, wOBA attempts to properly value a hitter’s outcomes, rather than treating all hits or times on base as the same.
One thing to remember: not all hits are equal. We see deficient thinking in the calculation of batting average, for example, where a single has the same value as a home run. OBP also assumes this, but at least takes into account walks. SLG attempts to take into account the difference in types of hits, but does so inaccurately (is a home run worth 4x as much as a single? No.)
wOBA takes the run values (yearly constant that tells us how much the event contributes to scoring runs) of each distinct offensive event and properly weights each outcome to measure a hitter’s overall offensive value. It also scales to OBP, so league average wOBA will always equal league average OBP, which is nice!
To summarize wOBA simply, if you want to know how well a hitter contributes to run scoring for their team, wOBA is an accurate representation.
Weighted Runs Created (wRC)
wRC is based off of wOBA and attempts to measure a player’s total offensive value in terms of runs.
Equation taken from FanGraphs
What this equation is doing (from left to right) is taking the difference of a player’s wOBA and the league-average wOBA (League wOBA), then dividing that by the wOBA Scale, which is a constant that can be found online for a given year very easily. Thereafter, you simply take the league’s runs per plate appearance (which can also be found online) and multiply that by the player’s total plate appearances.
Let’s run through an example. In 2024, Shohei Ohtani had a .431 wOBA in 731 plate appearances. The league average wOBA was .310, the wOBA Scale is 1.242, and runs per plate appearance was .117 (all found here). Simply plug these numbers in:
(((.431 – .310) / 1.242) + (.117)) * 731 → Shohei Ohtani had a 156 wRC in 2024.
wRC measures a hitter’s raw production, however it is not park or league-adjusted. For that data, let’s turn to wRC+.
Weighted Runs Created Plus (wRC+)
wRC+ is a measure of a hitter’s offensive value, adjusting for park and league factors.
League-average wRC+ is always 100, meaning that a player with a 110 wRC+ is 10 percentage points above league average and a player with a 90 wRC+ is 10 points below league average.
Equation taken from FanGraphs
This equation is admittedly terrifying, but it’s rather simple. From left to right in the numerator, we’re simply finding the number of runs above average a player contributes to his team per plate appearance and then factoring in the ballpark that player plays in, which could positively or negatively affect the final number.
The denominator is just wRC per plate appearance in either the AL or NL (whichever the player you’re looking at plays in) and then finally we multiply by 100 to make a nicer number.
In 2024, Shohei Ohtani’s 180 wRC+ helped him take home his 3rd (first NL) MVP award.
What’s great about wRC+ is you can directly compare players’ offensive value without having to incorporate the park they play at or the era they played in. Want to compare Babe Ruth’s 1920 to Aaron Judge’s 2022 at the dish? wRC+ tells us Babe Ruth was the more valuable hitter: Ruth’s 225 (!!) wRC+ trumps Judge’s 206 wRC+ (Judge did play more games…). Want to compare a Colorado Rockies hitter to a Seattle Mariners hitter provided the differences in climate? wRC+ is the way to go.
As is the truth with all advanced data in baseball, nothing is more important than context.
To summarize…
wOBA and wRC+ are two offensive statistics recently developed, but slowly taking over the game of baseball as we know it.
wOBA tells us exactly how valuable the outcomes from a certain hitter were and scales that to OBP to make it neat and easy to understand. wRC+ goes one step further and tells us how good that was across parks and across leagues. It allows us to do an apples to apples comparison when otherwise that wouldn’t have been appropriate.
I will most definitely be referencing these statistics in all my analyses of offensive production, so they are supremely important to know. But also, they present a concept worth knowing across any industry – certain events hold more weight than others, and it’s important to know just how much weight.
Inner Half 