SF Giants’ Birdsong learned his signature pitch on TikTok — and it could make him ‘elite’

CINCINNATI — It was sometime last year during spring training when Hayden Birdsong was engaging in a Gen Z pastime: scrolling TikTok before bed.

The algorithm fed the Giants pitcher a savory yet unsubstantial diet of short-form content. All the videos were forgettable. All but one — the one that introduced him to what would become his signature pitch. And to bullpen coach Garvin Alston, that pitch has dramatically raised expectations for the 23-year-old.

“It has changed him from...