It’s been a big week here at Wahoo’s on First. As you may have seen, we released not one, not three, but two new and improved versions of our Simple WAR Calculator in the past few days.
But why the change? What’s different about the new calculators, and why are they better than the original?
The original calculator’s offensive value estimations were based on Should Hit, a revolutionary innovation by the incomparable Bradley Woodrum. Should Hit (or “ShH”) used a player’s walk, strikeout, home run, and hit rates to estimate his wRC+ (weighted runs created-plus). The calculator calculated a player’s offensive runs created as a function of his ShH and plate appearances.
Version 1.1 uses the same method of estimating offensive value, but it replaces Should Hit with Woodrum’s newer and even better wRC+ estimator: Fielding Independent Offense (FIO). FIO is more accurate than ShH, especially for faster players—unlike its predecessoe, it takes stolen bases into account.
Version 2.0 is different. Rather than using a wRC+ estimator, its offensive value calculations are based on OPS+—which, as Tom Tango has noted, is roughly interchangeable with wRC+.
While not its original intention, OPS+ generally provides a more accurate estimate of wRC+ than ShH or FIO because it adjusts for specific run environments. ShH and FIO are calibrated to the average leaguewide run environment from 2009-11. But the game has changed quite a bit in that span of time, and even within the same league and season park factors can create vastly different run environments. OPS+ can be easily adjusted for any run environment—and so, by extension, can the Simple WAR Calculator v. 2.0. (This was not at all meant as a slam on Woodrum’s work, which is truly groundbreaking and was the original inspiration for the calculator.)
If you’re looking to get the most accurate value projections, go with Version 2.0. If you want to see how improvements or struggles in each fact of a player’s game affects his value, play around with Version 1.1. Either way, you’ll be better off than you would have been with the original.