Power Pros Forum

Can someone explain Fangraphs' Pitch fx to me?

1) The pitch types. What do FA, FT, CH, etc. stand for? (Yes, I know CH = changeup)

2) Movement. What does a negative number represent (i.e. Verlander's 4SFB is said to have around -10 inches horizontal break and about 8 vertical. No comprendo!)

3) Suppose FA means fastball. Does that include just 4SFB or does it also count 2SFB, CUT, SPLT?

4) Power Pros related question! Does Power/Brk Ball P count a 2SFB as a fastball or a breaking ball?

FA = fastball
FF = four-seamer
FT = two-seamer
FC = cutter
FS = splitter
FO = forkball
SI = sinker
SL = slider
CU = curve
KC = knuckle curve
EP = eephus
CH = change
SC = screwball
KN = knuckleball
UN = unknown

Every pitcher is unique, so the labels aren't always perfect - plenty of gray area between the two-seamer & sinker, slider & curve, splitter & changeup, etc.

Movement . . . imagine a theoretical pitch that has no spin (or laces) as it travels across the heart of the plate. Vertically and horizontally it is 100% neutral, and we can say that pitch is point 0.

As for decoding break, negative vertical is usually generated by some degree of top-spin (curves, slurves, big sliders, screwballs, sidearm fastballs/changeups). Positive vertical is caused by backspin (fastballs, cutters, changeups, tight sliders, sidearm breaking balls). Negative/positive horizontal depends on the pitch, but also the hand a pitcher throws with, but fastballs and changeups usually have some degree of tail and move in the opposite direction of breaking balls.

Spin * Velocity = Movement (more or less), which is why a good 2-seam fastball generates so much movement.

Check out TexasLeaguers for some dynamite PitchF/X tables and info.

PwrP impacts the frequency of the 4SFB and 2SFB. BrkP impacts the frequency of every other pitch, including SIFB and CUT.

Thanks!