Glossary: Pitch Tunnels

Break:Tunnel Ratio - This stat shows us the ratio of post-tunnel break to the differential of pitches at the Tunnel Point. The idea here is that having a large ratio between pitches means that the pitches are either tightly clustered at the hitter's decision-making point or the pitches are separating a lot after the hitter has selected a location to swing at. Either way a pitcher's ratio can be large.

This stat tells us the likelihood that a particular pitch will be called a strike based on a variety of factors. CS Prob is calculated on every pitch thrown by a pitcher. CS Prob is a proxy for control, or the ability of a pitcher to throw strikes.

Plate Differential - This statistic shows how far apart back-to-back pitches end up at home plate, roughly where the batter would contact the ball. This includes differentiation generated by pitch break and trajectory of the ball (which includes factors like gravity, arm angle at release, etc.).

Release Differential - When analyzing pitchers, we often talk about consistency in their release point, pointing to scatter plots to see if things look effectively bunched or not. This stat measures the average variation between back-to-back pitches at release.

Tunnel Differential - This statistic tells you how far apart two pitches are at the Tunnel Point—the point during their flight when the hitter must make a decision about whether to swing or not (roughly 175 milliseconds before contact).

Speed Changes - This is the average difference, in seconds, between back-to-back pitches.

This is the number of sequential pitchers in the sample for the given selection.

This is the selected pitches for drilling down on a specific sequence.

This is the selected pitches for drilling down on a specific sequence.

This stat details the additional called strikes outside the reference zone that are credited to the pitcher after accounting for catcher, umpire, pitch type, etc. This stat is calculated on all called pitches (i.e., balls not in play). Pitcher CSAA is a proxy for command, or the pitcher's ability to locate the ball precisely. Base "CSAA" values are the "expected" or "mean" values for each player. We're now also pleased to provide, for seasons 2008 to the present, the standard deviations (SD) for both CSAA and CSAA / Framing Runs. SDs allow you to calculate uncertainty intervals to say how certain we are that the true measurement of the player falls within the defined interval.

Break Differential - This stat tells us how much each spin-induced movement is generated on each pitch between the tunnel point and home plate. Think of this like PITCHf/x pitch movement, except that it is only tracking the time between the Tunnel Point and home plate.

Release:Tunnel Ratio - This stat shows us the ratio of a pitcher's release differential to their tunnel differential. Pitchers with smaller Release:Tunnel Ratios have smaller differentiation between pitches through the tunnel point, making it more difficult for opposing hitters to distinguish them in theory.