In major league baseball, the pitcher's mound is 60 feet from the batter. if a pitcher throws a 89 mph fastball, how much time elapses from when the ball leaves the pitcher's hand until the ball reaches the batter?

Hitting can be broken down into three segments; SEE, REACT, SWING. You watch the ball in the pitcher's hand during the windup and you watch the ball leave the pitcher's hand when it is thrown and you watch the spin of the ball as it comes towards the plate. That is SEE. You determine what the pitch is (fastball, curveball, etc.), you determine where the ball is going to go and you determine whether it is headed towards an area that you think you can get good wood on it. That is REACT. You swing if you like the pitch or don't swing if you don't like the pitch. That is SWING. It doesn't make any difference whether you are playing with a tennis ball or a golf ball or a baseball. The theory and mechanics are the same. So, to answer your question I would say the more you practice the better you will be, regardless of the type of ball you use to practice with.