Baseball Hacks

Plot Spray Charts

Plot charts showing where players hit the most baseballs.

Many baseball players tend to hit balls to some parts of the field more often than to others. Perhaps the best illustrations are sluggers Jason Giambi and Barry Bonds. Each player hits the most balls to the right side of the field. When these guys are batting, the opposing defense will shift toward the right side of the field.

Managers use a tool called spray charts to decide where to position defensive players because it shows where baseballs are most likely to be hit. This hack teaches you how to plot spray charts, using data from MLB Gameday. You can find similar charts on the Internet (for example, try the Hitting Chart links for individual players at MLB.com), but there are some advantages in plotting these yourself. First, you can choose any set of players to plot. Second, you can focus on certain situations and matchups. Finally, you can draw some easier-to-read charts, such as hexagonal bins.

For this hack, we’re going to use the matchup data we derived in “Find Data on Hit Locations” [Hack #29] . This file includes game IDs, game dates, teams, a hit indicator, x and y coordinates of each ball in play, the name of the pitcher and batter, and the way the play was scored (i.e., single, groundout, or home run). We’ll load this data into R, set up axes to show the field, and then plot hits and outs.

In “Find Data on Hit Locations” [Hack #29] , we created a file containing the results of each hitter-pitcher ...