Baseball metrics have twin goals: They try to reflect player value in what has happened, but they also try to be indicators of future performance.
Both are valid goals, but they sometimes confuse fans. The reflective runs-based pitching WAR at Baseball-Reference is a different stat than the predictive FIP-based pitching WAR at Fangraphs.
A new stat Baseball Prospectus has introduced for 2019, deserved runs created plus, leans toward the predictive side.
Like Fangraphs’ weighted runs created plus, DRC+ weighs each offensive event according to its value. A home run is more valuable than other hits, double plays hurt more than strikeouts and much more.
It’s all adjusted for ballpark factors and opposition, then normalized to a 100-point scale so that a 100 DRC+ signifies an average hitter.
DRC+ differs from wRC+ in that it adjusts for hitter responsibility for each act. It gives more weight to events most in a hitter’s control. Walks and homers are pitcher-vs.-hitter outcomes, so hitters are rated as more responsible for those than they are for singles, where defense also is a factor.
The goal is to rate a hitter’s value based on his own efforts, with a minimum of outside factors.
Baseball Prospectus ran DRC+ back through baseball history and says it correlates better to future results than other metrics.
We can get an inkling of how it works with Ian Happ, who has started this season with the Cubs’ Class AAA Iowa affiliate.
With the Cubs last season, Happ hit .233 with 15 homers, 70 walks and 167 strikeouts in 462 plate appearances. The homers and walks added enough value to give Happ a 109 wRC+, meaning he was 9 percent more valuable than the average hitter.
But when DRC+ determines how much of that was Happ’s responsibility, a .362 batting average on balls in play suggests his average would have been even lower with normal results.
League-average BABiP was .297, and Happ had not established that his normal BABiP should be so far above the average. A certain percentage of his 75 non-homer hits is seen as due to defense and chance, so they are given a lower weight in his DRC+. The result is an 88 DRC+ that would suggest a decline to weaker outcomes.
Javy Baez, with a low walk rate being the main reason, also had a lower DRC+ (120) than wRC+ (131). That still was good enough for the second-highest DRC+ in Chicago, behind Anthony Rizzo’s 128 (vs. a 125 wRC+).
On the South Side, Jose Abreu led the way with a 114 DRC+ that matched his wRC+. Matt Davidson, since departed for the Rangers, was next with a 101 DRC+ that was three points below his wRC+, and Daniel Palka was at 100 DRC+ vs. his 109 wRC+.
No metric is perfect. There’s too much unpredictability in human performance. But each step in the direction of predictiveness helps as analytics and scouts work together in roster-building.