A couple days ago, Dave Appelman introduced an amazing new feature to FanGraphs: Minor League Leaderboards. This new feature will allow us track all of our favorite prospects, and learn the names of budding stars we otherwise would have missed. While the Minor League Leaderboard is an incredible tool, it is helpful, if not imperative, to take into account a player’s age and playing level. If I told you that a player had a triple-slash-line of .331/.405/.664 you might think he is a stud, but if he’s 28 and in Triple-A, it is safe to assume that the player is no prospect (there are of course exceptions).
Last season the average age of a rookie was 24.5 in Major League Baseball. This is a helpful starting point when evaluating Triple-A players. The average age of players in Triple-A last year was 28, and the vast majority of players in Triple-A are older than their Major League Rookie counterparts. While there are some 25 year olds in Triple-A that will make impacts on their respective teams, few significantly older should be considered prospects.