I don't think that's what the writer is saying. He specifically writes this: "Every hitter’s approach needs to be neatly tailored to their skill set, and Kepler, Arráez, and Garver nicely demonstrate the flexibility of the Twins’ individual plans for their hitters these days. They don’t need to make major adjustments in the way they approach the first pitch." Aggressive does not mean they have to swing. It just means they should be ready to swing if they get a good pitch.