Jacob deGrom wound up to deliver a warmup pitch and then totally forgot the ball
Warmup pitches prior to the start of an inning are not the most integral part of a pitcher's routine. He's already had plenty of time to warm up before the game, after all, and now he just needs a few quick tosses to make sure his arm stays loose.
Still, that being said, we can't recommend the strategy
Maybe he needs a quick bullpen session with staff ace