And I fully agree with Kimmi and will back this view.
The manager's most important job is pre-game preparation and overall strategy, not specific little moves within the game. He has to think of the future as much as the present when utilizing players. He has to put them in a position to best utilize their skills. This means knowing who hits well against certain pitchers and in certain situations. It means putting out the best lineup for the next game, but not down to the exact batting order. The fine details in baseball are much less important than the big picture. Strategy is about the game at hand and the long term season balanced against each other. Baseball is not a strategic game for the most part when it comes to the details of game moves. It is strategic in the larger picture.