# Pitch F/X

Ever wonder the exact location, movement, speed, rotation, spin angle of a pitch? With Pitch F/X, every ball thrown in the majors is calculated to a science. It’s pretty awesome but even after spending hours looking at the data, it can be a bit confusing as to what the variables mean and how they are meaningful. I’ll try to explain most of the variables to the best of my abilities. I’ll be using F/X data from Dallas Braden’s perfect game on May 9, 2010 against the Tampa Bay Rays.

Picture yourself as the umpire or catcher looking towards the mound and that is exactly what the above plot is showing us. Thus a right-handed batter will be on the left side of the graph, while a left-hander is on the right side. I also superimposed a strike-zone to show the strike-ball nature of each pitch.

Another important graph is to look at the total vertical/horizontal movement of pitches. Again, this is in perspective of the catcher or umpire. The movement of a pitch is the difference of a projected straight line from a pitcher’s release point and the actual location of the ball once it reaches home plate. An example is Braden’s slider movement (the purple points); it’s motion slides horizontally, away from a lefty, or towards a righty. The graph also tells us his fastball movement is going upwards as it approaches home plate.

You’ll also notice the cluster of red and blue points that tend to be inner mixed meaning two different types of pitches are having the same kind of movement. The two pitches are the change up (which deceives batters by having identical fastball movement, but its speed is drastically slower) and a two seam fastball. The only difference between these two pitches is their speeds.

From this plot we can see the speeds of each type of pitch. As I was stating earlier about the two nearly identical pitch movements, Braden’s change up (CH) was around the 65 MPH range, while his two-seam fastball (SI) was around the low-80s.

One question after looking at these plots may be how the system dictates or knows what kind of pitch is thrown. The F/X system uses algorithms to dictate types of pitches. Based on the history of pitches thrown, we have a general idea of how each type of pitch can be characterized. Sometimes the algorithms are wrong but in general, they seem to do a great job with assigning pitch types.

Something to take away from these graphs is that it looks like Braden worked to locate his pitches inside the strike zone (a 71% strike-thrown percentage) well. And if you find anything amazing about his change-up on May 9, it’s that it looked almost identical to his two-seam fastball, just slower by an average of 15 MPH. That will get you a bunch of misses or very field-able balls any day. I’m sure after the game, Braden partied a bit like CB (IceBat sure did):