An Annual Reminder from Eric Hosmer and Adam Jones
If you woke up this morning, looked at the WAR Leaderboards for position players and saw Mike Trout, Jose Altuve, and Manny Machado near the top, you might have had an inclination that all is right with the world. After all, those three players are some of the very best in major-league baseball, and we would expect to see them at the top of the list. Of course, when you look closely at the leaderboard, it’s important to note that there are 171 qualified players. To regard the WAR marks as some sort of de facto ranking for all players would be foolish. For some players, defensive value has a large impact on their WAR total, and it’s important, when considering WAR values one-third of the way into the season, to consider the context in which those figures.
“Small sample size” is a phrase that’s invoked a lot throughout the season. At FanGraphs, we try to determine what might be a small-sample aberration from what could be a new talent level. Generally speaking, the bigger the sample size, the better — and this is especially true for defensive statistics, where we want to have a very big sample to determine a player’s talent level. Last year, I attempted to provide a warning on the reliability of defensive statistics. Now that the season has reached its third month, it’s appropriate to revisit that work.