In order to narrow the number of pitches we would review down from a total of 23,827 tracked pitches by the St. Louis staff to a manageable level, we came up with a scoring system for every two-pitch, same-batter sequence.
We focused primarily on velocity, location, and break differential, each scaled to provide equal weighting to the pitch’s total score.
One of the best sequences we identified this way were fastballs high-and-in followed by breaking balls low and away.
Think about a Carlos Martinez two-seamer running in on the hands of a right-handed hitter, followed by one of his patented sliders diving low and out of the zone.
Sometimes, however, pitches are nasty because they look nearly identical to the hitter. We know that as pitch tunneling, and successful tunneling can lead to some of the most helpless swings.
To capture this aspect, we added to our scoring system to reward sequences that featured similar break, movement, or velocity.
Using this method, a perfectly tunneled change-up following a sinker would score just as well as the fastball-slider sequence detailed above.
Overall, then, there are six ways a sequence can score well:
a velocity gap
matching velocities
movement differential
tunneled break
changing spots
tunneled location.