Armstrong’s curveball (Statcast categorizes the breaking ball as a slider) follows his fastball’s lead with a 51.4% zone rate, but batters have punished the curve for finding the zone with such certainty: a 90.4% Z-Contact rate is partly to blame for a .343/.378/.457 slash line, as the curveball’s strikeout rate plunged from 63.6% in limited 2018 work to 8.1% last season.
Chalk Armstrong up as having serviceable four-seamer velocity (maxing out around 96 mph and hovering just below 94) and an unimpeachably great spin rate, reaching Statcast’s 96th percentile. Armstrong exhibits good command of the heater (55.9% zone rate) and the pitch rewards his reliance with a solid 30.5% strikeout rate.
There’s a theme to sense in Armstrong’s reliable zone location: His cutter notched a 53.4% zone rate, rivaling his curveball and four-seamer. The strikeout rate on the pitch jumped from 4.2% to 15.2%, but his walk rate is also up there in double-digits (11.4%).
His true four-seamer was a much more effective pitch than his cutter as it had a 24.4% whiff rate and .222 wOBA allowed.
He increased his cutter usage from 18.6% in 2017 to 38.6% in 2018. The results were not good as it allowed a .300 batting average and .341 wOBA and a poor 11.9% whiff rate.
Armstrong’s best whiff pitch (45.8%) his slider was effective in a small sample size limiting opposing hitters to a .080 wOBA.