Weighted Grounded into Double Play Runs (wGDP) is the number of runs above or below average a player has accumulated based on their ability to stay out of double plays. This isn’t something we talk about a lot when analyzing a player, but hitting into a double play is making two outs instead of one and making outs is always a bad thing.
wGDP is based on how many double play opportunities a player arrives in and then how often they hit into a double play when those situations come up. If a player is in 20 double play opportunities (man on first, less than two outs) and never hits into a double play, he is more valuable than a player who hits into five double plays even if they both reach base themselves the same number of times. To find a player’s wGDP, we take the average rate of GDP in GDP opportunities and apply it to the number of opportunities the player had. If they have fewer than average GDP, they get a bonus and if they have more, we take runs away.
The actual calculation involves subtracting the run value of the extra out. The player is already charged for the out they make themselves, but this now charges them for getting the base runner out as well.
It’s a minor addition to the site and to WAR, but wGDP gives players credit for not hitting into double plays no matter how they avoid them. If they run well out of the box, great. If they don’t hit grounders with men on first, that’s cool too. The key is that when you use a statistic like wOBA to measure a player’s offensive ability, you’re only counting what happens to them. That’s mostly good, but when they hit into double plays, someone has to be responsible for that out.
This metric is scaled to their number of opportunities, so if you never hit with men on base, you aren’t at a disadvantage, but if you’re consistently killing more of your own runners than average, we want to measure that.
How To Use wGDP:
Using wGDP is simple. It’s measured in runs above or below average, just like all of the other run value stats. If a player has a positive wGDP, it means they are adding runs to their team by avoiding double plays. A negative value means they’re hurting their team with all the double plays.
The range is generally pretty small, but we add it into BsR and ultimately WAR to soak up as much information as we can.
The numbers will bounce around year to year, but generally the range of wGDP looks like this:
Things To Remember:
● wGDP does not included line drive double plays.
● wGDP doesn’t control for things like handedness or batted ball location. It’s just about opportunities and double plays.
● The metric is relatively new, so we haven’t seen public analysis on how quick it becomes predictive, so stay tuned.
Links To Further Reading:
Neil Weinberg is the Site Educator at FanGraphs and can be found writing enthusiastically about the Detroit Tigers at New English D. Follow and interact with him on Twitter @NeilWeinberg44.