Challenging the worth of traditional offensive stats doesn’t seem necessary to many fans, and understandably so. I mean, we crown BATTING CHAMPIONS and decide who has a shot a the MVP based on these suckers, for cripes sake. In large part we PAY players based on the stuff. However, these numbers alone don’t really tell us what we need to know. Enter Weighted On Base Average (wOBA) and Weighted Runs Created (wRC). These stats manage to give us much more information about the talent and performance of a hitter, and they’re packaged in tidy, relevant formats.
wOBA does an important thing at the front end. It places a certain value, or statistical weights, on different hitting outputs. In other words, when calculating wOBA we consider a double to be more valuable than a single, and so on up to a dinger. The weights placed on singles, doubles, triples, homers and walks are based on historical data from tons of seasons. Basically, really cool baseball geeks determine on average how often these outcomes lead to runs when compared to each other, and from there they weight (mathematically value) each outcome accordingly. Through a little more math wizardry, the output of all hits and walks are converted to an output that works like Batting Average and On Base Percentage. wOBA is always scaled so that league average OBP and league average wOBA are the same, which is usually right around .320. Here’s a quick and dirty way to assess a player’s production with wOBA:
wRC takes wOBA a step further and converts a players production into runs as a unit. This is practical because it allows us to talk about a hitter’s value in terms of how many runs he alone has been worth, based on the historical weights from wOBA and his actual results. If you’re using this stat to compare players to others or to an average level of production, it’s best to use the wRC+ version. As opposed to cumulative runs accountable to a player, wRC+ takes the output of a hitter at any point in his season and adjusts it to reflect an entire season of At Bats (set at 600). The “+” version also adjusts for differences between the National and American Leagues, and between different ballparks wRC places every player on an even playing field. To be clear, wRC and wOBA do not account for these factors.
Also, 100 wRC+ is scaled so that it reflects league average performance, which is always set at a nice round 100. Each whole number above or below 100 represents one percentage point below or above league average production (again, based on wOBA). For example, if Sid Bream has a 175 wRC+, then he is 75 percentage points higher than the average in terms of offensive output. This makes the stat easy to use, even without looking at a list of other players’ wRC+. Being that it is also ballpark- and League-neutral, wRC+is quite handy indeed.
Here’s a quick and dirty way to assess a player’s production with wRC/wRC+:
As always, we need to look at a number of different statistics if we want to get a clear picture of a player’s talent and performance. When you’re looking for a quick synthesis of how a hitter has performed though, you really can’t go wrong with wRC+.
[a big thanks to Neil Weinberg and others at Fangraphs for allowing us to use the above graphics, and for generally being available via twitter to answer my questions about the stats featured in our Glossary. If you want to learn more than we are teaching you, GET STARTED HERE.]
Lead Image retrieved from http://7-themes.com/6819036-babe-ruth.html