Isn't a manager's role in baseball more like being a errand boy?

I heard that in the MLB, more than half of the teams
analyze pitcher substitution timing,
opposing pitcher's pitch sequencing,
using AI.
Yesterday, Tampa's unexpected pitching change,
or the Dodgers' strategy to load the bases in the 8th inning of Game 1—
which succeeded but still lost the game—
was this actually the manager's judgment, or was it a value analyzed by AI?
They say for a manager, it's best to just be a nice guy.