It's possible if his arm is fatigued he relies on the curve a lot more. Or any hook. Appears to be dead arm would demonstrate up nor prominently on speedy ball velocity, not everything hooking. Libby pitched 86 innings final year mostly an inning or two at any given time. https://www.dailypioneer.com/2021/state-editions/punjab-govt-to-approach-global-manufacturers-to-purchase-covid-vaccine.html