It is a factor to convert a wOBA point into a run.

If we did the equation with OBA instead of wOBA and without the wOBAScale factor, we’d get Baserunners above average or Baserunners Created. If we then apply wOBA instead of OBA without the wOBAScale factor, we get Baserunners above average or Baserunners Created, adjusted for the advancement of other runners.

The final step is the wOBAScale factor to convert from baserunners to runs. Or, the probability of one run scoring, given the state of the runner reaching base. (Hmm, this phrasing reeks of the hypergeometric distribution, but I hope that’s not what we need here.)

I hope I got the arithmetics right…

]]>I know you don’t include Reached Base on Error in your calculation, but why is it included in Mr. Tango’s formula? Why should a batter get credit for the other team making a mistake? Thank you very much. ]]>

Could you please explain the wOBA Scale calculation? I see that pacity0champs already asked, but no one anwered, so I’ll ask again. Thanks! ]]>

I may be stupid (well I am but this individual effort may also be less than intelligent) but, what is the value for wOBAScale?

I have been reading on all stats starting from linear weights on and from linear weights to WAR the only thing I’m missing is this value.

Thank you preemptively for filling me in.

DLR

]]>I believe Bill James forecasts (or at least did) for a more limited set of players than other systems.

If so, is averaging his forecasted players basically “selectively sampling” a group of above average players, so that it ends up excluding a lot of marginal, replacement type players whose predicted performance would otherwise pull down the average of forecasted players closer to actual league averages?

I think that is what I gathered from this (http://tinyurl.com/3mb6ky) thread at The Book blog, which seemed to indicate Marcel only failed to forecast like 5% of plate appearances while with James, “10% of MLB PA were either unforecasted or unmapped.”

I’m not sure if its correct but my sense too is that it might be helpful to use the same baseline for an apples to apples comparison.

Thanks again for your great site.

]]>Basically, the lgwOBA for the Bill James projections comes out to .346 instead of .328. That’s where the difference is, and since wRAA is runs above average, the average runs is considerably higher in the Bill James projection than it is the Marcel. Maybe I should be using the same baseline so we have an apples to apples comparison.

]]>Question about the plate appearances data are you using to calculate the projected wRC/wRAA calculations based on the Marcel and Bill James’ projections?

For example, Marcel projects Brian Roberts to have 546 at bats/624 plate appearances, a .346 wOBA and a 7.6 wRAA.

Bill James projects Brian Roberts will have 623 at bats (no PA projection), a .350 wOBA but only a 2.6 wRAA.

Shouldn’t the wRAA for the Bill James projection be higher than the wRAA based on the Marcel projection, as James thinks Roberts will have a higher wOBA and also have more at bats than Marcel?

Thanks.

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