This article is free for anyone to read, but please consider becoming a Patreon subscriber to allow me to keep writing posts like this one. Sign up to receive articles like this one in your inbox here.
On Thursday, FanGraphs ran a piece explaining that they were making a significant change to how they calculated wins above replacement. There’s nothing wrong with doing so, of course — it’s good that FanGraphs is making a change to how they measure defensive value, especially since what they are changing has been a known issue for some time now amongst people who pay attention to such things. These kinds of changes are how we end up with better understanding of which players are the most valuable, the least valuable, and so on. WAR isn’t the be-all, end-all, even if some treat it as such, but it can still be useful for analysis, so prioritizing its accuracy is necessary.
It’s not a static figure, though: historical WAR changes when the inputs change. Which is why FanGraphs’ list includes a number of tables that do things like show that Nick Ahmed has actually been worth nearly seven more wins above replacement in the last five full seasons plus the pandemic-shortened 2020 campaign than they were giving him credit for: from 2016 through 2021, Ahmed was rated as producing 4.8 WAR, but the change to the formula now has him at 11.6 over the same time period. Baseball-Reference, for what it’s worth, already had Ahmed at 11.5 WAR from 2016 through 2021, largely on the strength of his defensive output.