1/11/13

Michael Friere - What Are Sabermetrics - wRC

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Last week, in Part Four of this series, we looked at wOBA, which is more precise then other, similar statistics such as OBP or even OPS (since OPS is rooted in using SLG, and that can be slanted since a single isn’t always half as valuable as double, etc).
In this week’s installment, I want to touch on a different statistic, referred to as Runs Created, or RC. This statistical measurement device was created by the legendary Bill James, and it is primarily used to estimate the number of runs a specific hitter contributes to his specific team, over the course of a set time (usually a full season, but it can also be used over partial or full career time frames). It can also be used as a predictive took in a larger context for both players and entire teams.
Here is a basic quote from Mr. James, that was the result of a question asking why the statistic was created.
With regard to an offensive player, the first key question is how many runs have resulted from what he has done with the bat and on the base paths. Willie McCovey, for example, hit .270 in his career, with 353 doubles, 46 triples, 521 home runs and 1,345 walks, but his job was not to hit doubles, nor to hit singles, nor to hit triples, nor to draw walks or even hit home runs, but rather to put runs on the scoreboard. How many runs resulted from all of these things?

I think it is pretty easy to say that Willie McCovey was a hell of a ball player, regardless of the statistic that is used.   However, like most statistical formulas, Runs Created (or any of the other statistical formulas cited in this series) can be extremely useful in identifying underrated players. As we are quickly learning in the “new Mets’ era”, there are significant salary restrictions on what Sandy and Co. can do going forward. Making the best use of the available funds will be more important then ever in our slow climb back to respectability.
At the end of the day, only one thing really matters and that is which team won the ball game? The team that scores more runs, wins the game (I think of Herm Edwards every time I write that first line.......you know the commercial “you play to win the game”). A very simple concept, but a bit harder to define.

Unlike some of the other statistical formulas we referenced in the past few installments, Runs Created (RC) can be expressed in a few different ways. The first formula was;

RC = A X B divided by C
  • A = On-base factor
  • B = Advancement factor
  • C = Opportunity factor
Another version, that included more common variables like slugging percentage, on base percentage, etc;
RC = (H + BB) X TB divided by AB + BB
However, there are other versions that attempt to account for additional factors, like stolen bases, etc;

RC = (H + BB - CS) X (TB X (.55 X SB)) divided by AB + BB
In 2002, additional changes were made to have the formula more accurately reflect the impact of the specific player (earlier versions of runs created overestimated the number of runs created by players with extremely high on-base and slugging factors).    So, if you see other versions of this formula, that is most likely the reason why.

I know....make it stop! This is starting to look like a scary, statistics class nightmare!
I also know that most fans (including yours truly) are probably not going to figure these things out from scratch. Instead, I will use any number of baseball statistical sites to obtain the proper data and make my comparisons from there. But, sometimes knowing how a larger formula comes together is helpful when you look at the end result (these formulas are merely presented as a reference).
So, let’s look at this past year in our favorite game and list the top producers in Runs Created (RC) for both the NL and the AL;
Miguel Cabrera (DET) created 139.6 runs last year and Matt Kemp (LAD) created 135.9 runs! Taking this a step further, the Tigers scored a team total of 787 runs, while the Dodgers scored 644 runs. Using a simple percentage formula, Cabrera was responsible for approximately 18 percent of the Tigers runs, while Kemp was responsible for approximately 21 percent of his team’s total! It’s pretty easy to see why they are both considered among the best at their respective positions (and why Kemp just signed a huge contract extension).
Since someone will ask, our top producer was Jose Reyes (sorry for the reference, Mack) with 105.1 runs created, which was good for 21st in all of baseball (or the 75th percentile, figured by dividing the number in question by the overall leader’s figure). Is Jose talented? Yes and we will feel the impact of his loss. Whether it is sensical to keep him, when you factor in cost and injury factors is another matter.
As the offseason unfolds, keep this statistic in mind and use the percentile measurement to see just where free agents, trade targets and even minor league prospects rank. It gives you, the fan, another tool to see just how valuable the players in question actually are.

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