One of the most important details about stats is that on a long enough time line any stat will give you an indication of if a player is good or not. The effort put into advanced stats is to shorten the timeline. Think about pitching stats. You could wait through a players career to see how many wins they end up and how many seasons they have with 15+ wins, but sports fans are an impatient lot and waiting until someone’s career is almost over isn’t a good way to know if they are really good right then.
ERA does a slightly better job of this but it doesn’t measure exactly what a pitcher does. Three years of ERA should be enough to tell what a players true talent level is, but front offices have to make decisions on less than three years of data and averages of that long of a time period can vary dramatically year to year. FIP is thought of as a more predictive stat because it doesn’t fluctuate as much from year to year as ERA meaning a smaller sample size is needed to judge a players true talent level.
Sample size is just as important for batters. Unlike pitchers however rate stats haven’t caught on as much with position players as they have with pitchers. It may be because of the traditional triple crown stats of BA, HR, and RBI and the weight that has been traditionally put into those stats. Two of the three are counting stats and batting average tells a very limited story of what a player is doing at the plate. Most baseball fans would understand that if a player has 15 homeruns and 40 RBI in June that he is off to a pretty good start.
While numbers through June are good they aren’t always predictive of where a player will end up at the end of the season. In 2012 29 year old journeyman Brian LaHair of the Cubs was hitting .298/.382/.564 through June 15. He looked like another late bloomer like Jayson Werth or Michael Morse finally putting it together, but the season doesn’t end in June. LaHair’s hot start helped him to make the All-Star game, but after the break he hit .202/.269/.303 and found himself out of a job at the end of the season. LaHair had a couple hot months, but then fell off drastically. As the last generation is apt to say water found its level.
Much the same can be said for Ryan Zimmerman’s season, but in reverse. Before getting a cortisone shot on June 24 Zimmerman was hitting .218/.285/.305 and after receiving the shot .321/.383/.584. Ryan Zimmerman is a much more talented player than what was on display in the early part of the 2012 season and after getting his shoulder to feel better he put up numbers more in line with what is expected from Ryan Zimmerman. Zimmerman, at 28, is in the midst of his prime and should be having his best offensive years. That was put on hold a bit due to shoulder injuries, but his second half is more indicative of his true talent than the first half. Both, however, are small sample sizes. Ryan Zimmerman, or any player, over a given time period is most likely to hit around their career averages.
When looking at sample sizes it is important to take into consideration what is being measured. If all a person is looking for is who had the best week or month then a week or month is all that needs to be looked at. The understand should be that because the Brian LaHair’s of the world have a great April and May it doesn’t mean their true talent level is close to how they preformed during that sample size. The fact that Pablo Sandoval hit three homers in a World Series game doesn’t put him on the same level as Albert Pujols, Reggie Jackson, and Babe Ruth. Over the small sample size of one game Sandoval was just as good as those all time greats. That is what small sample sizes do. On any given day even the least of us can accomplish great things.
Small sample sizes make baseball fun. The understanding should always exist that a good game, a good week, or a good couple months doesn’t make a player good, but enjoying those accomplishments is what a fan does. I have always been a big proponent of baseball for the sake of baseball. How could I not be as a Washington Nationals fan, especially in 2007-2010? While I never believed that Pedro Astacio or Shairon Martis were good players I certainly enjoyed being at their complete games.