Yeah, the old EU tried to retcon this by saying the Emperor was using “battle meditation” to direct the Imperial fleet and once he died it all fell apart, but battle meditation has always felt like one of the dumbest concepts in the old EU.
I might have gotten used to the idea from the X-wing Miniatures game (Where Palpatine is a crew card that allows you to alter any one die you roll once per round), but I can see how that annoys people. And even if he was guiding them, I doubt he’d turn the tides entirely, the point totals of the two armies were far too large for Palp crew to be relevant.