Well, i'm no science buff but i do have some goold ole common sense:
You can't compare hitting a baseball (a moving object at anywhere from 50-100mph) to hitting a golfball which is STATIONARY.
Also, a golf ball compresses A LOT more than a baseball does. So, regarding newton's law of equal/opposite reaction, the "opposite" reaction from hitting the baseball (left arm pinching against the torso) is going to be a lot more than a golf...