Interpreting PITCHf/x Charts by Ben Duronio April 4, 2012 PITCHf/x charts can be found on each of the websites that carry the PITCHf/x database. Ranging from overhead views to graphed release points, these charts can be used for many different purposes. Above is a chart of an overhead view of Mike Minor’s 2011 season. He has the four standard pitches, and this chart shows where the average pitch landed and the trajectory the pitch took from his hand. His changeup has fade while his slider and curveball both break. While this is not the most useful chart for analysis, it is interesting to look at and see the trajectory and landing points of each pitch. This is the side view, from the first base side of the mound. Rather than the horizontal movement, this chart shows the starting and ending points along with the vertical movement of each pitch. His off-speed pitches drop the most, which is not surprising to anyone with any type of baseball knowledge. These charts taken from Texas Leaguers, but FanGraphs has its own section for PITCHf/x charts as well. This chart is his release point. He has a rather constant release point, with his curveball being on the high end and his fastball being on the low end. This is consistent with the typical pitcher, as a curveball usually requires a higher release point. This does not mean that he is tipping his pitch, it is just the nature of the curveball in comparison to other pitches. In order to gain the type of break and speed required from a curveball, the higher release point is necessary. Vertical and horizontal movement in conjunction with pitch velocity are shown in both of these charts. Keep in mind that gravity is not included in these charts, though you can find charts that do account for gravity on other websites. The slower pitches are altered more by gravity, but each pitch drops a decent amount when gravity is included. For a right-handed pitcher with an identical repertoire, the charts would flip. Minor does not generate a ton of horizontal movement with his breaking pitches, as the natural break he has on his pitches seemingly outweighs the movement he gets on his breaking balls. His fastball and changeup both tail in significantly. These two charts show the strike zone and every pitch that Minor threw over the course of the season. At Texas Leaguers, you can choose a single pitch and view these charts with less clutter. In looking at all of the pitches, the primary pitch used tends to dominate the chart. The strike to ball graph is a bit more useful. Minor tries to stay down in the zone, which could be a reason for his lower than average home run rate. That’s too quick of a conclusion to jump to, but that is the kind of interesting thing that can be viewed from this chart and then analyzed more in depth by viewing different pitches and looking at his stat page to determine batted ball rates and so forth. This chart takes data from each game and shows how often the pitcher threw each pitch. This could be useful in noticing any particular trend a pitcher has when their results alter. Maybe a pitchers stretch of four impressive starts after a slew of poor outings was due to a change in his pitch frequency. Coming to the player page to analyze the data may or may not show if that’s the case, but finding out the information helps understand if an actual change has been made or if the pitcher is just having a few good performances based on chance. This chart shows the velocity of each pitch in every start. Minor was pretty consistent last year, as there were not many big changes in his velocity in any given start. There are some pitchers who struggle with velocity or gain a good deal of velocity throughout the season, and the improved or declining velocity could be a reason for their more recent performance being much different than their past performances. These next two charts show the horizontal and vertical movement by start as well. Much like the previous two starts, noticing any particular change could be useful in pitcher evaluation. I hope this page helps you answer any questions you may have about PITCHf/x charts and what they determine. If you have any questions about the charts or believe something should be added to this section that we missed, please do not hesitate to ask.