This is an excerpt from Baseball Skills & Drills by American Baseball Coaches Association.
It is one thing to know the mechanics of hitting; it is another thing to develop this desired skill in the swing. The following few pictures and thoughts may help hitters process the skill information into mental pictures that they can simulate in their swings.
Relax the Body, Focus the Mind. A hitter who grips the bat too tightly and has a rigid body that is tied in knots is often asked to relax. To react properly to a pitched ball, the hitter's body must be relaxed, but his focus, concentration, and visualization must be sharp. He must understand this point, because when a hitter tries to relax his body, he often relaxes his concentration as well, creating a sloppy swing.
Relaxed Upper Body, Strong Lower Body. As we narrow down this relaxation, we want the hitter's legs to be firmly planted on the ground, feeling solid and strong. The upper body should be more relaxed and ready to react. The hands will more than likely control the relaxation of the top half. If they are tight, the rest of the upper body will be also.
Quickness, Not Muscle. The hitter should remember this: "If you think strong, you think wrong." The normal reaction when a pitcher is throwing hard is to swing harder. This, in fact, slows bat speed and normally does not produce base hits. A hitter should concentrate on quickness to the ball. This will normally shorten the path to the ball and will produce a more productive at bat.
Tall, Loud Back Side - Short, Quiet Front Side. As the hitter pictures his swing, he imagines the back side driving the front side out of the way. He does not want the front side to pull the back side through, an action that produces a longer, slower swing. In other words, a loud back side produces energy and force, and the quiet front side produces less initial action. In reality, both sides work together. But the front side often opens up too early, the hitter loses plate coverage, and the front shoulder pulls the weight forward, causing a slow, sweeping swing.
The hitter also wants to produce a mental picture of a tall back side. A hitter will often drop his back shoulder below the level of his front shoulder or collapse his back knee, causing the back side to cave in. This causes the hitter to cast the bat away from the direction of the ball initially and will eventually produce a bat arc that is in an upward path. Obviously, this is a longer bat path and breaks the rule of rotating all body parts in the same path. This is normally referred to as dipping.
React, Don't Think. This is just another reminder to the hitter that he cannot do much thinking as the pitcher is preparing to throw the ball. He should trust his stuff and simply react to the pitch.
Evaluate Own Talent. Every hitter can control some areas of the strike zone better than he can others. Each hitter should know where his pitch area is in relation to the strike zone. Early in the count he should avoid swinging at strikes that are not in that area.
Evaluate the Pitcher. The hitter can observe the pitcher before his at bat or learn from each pitch that the pitcher throws to him. A pitcher often falls into patterns. What does he throw when ahead or behind in the count? Where does he throw most of his pitches? Does he work the fastball both in and out?
Some good questions the hitter can ask himself are "Can he strike me out?" and "Does he have a nasty strikeout pitch?" If the answer is yes, then his thoughts should turn to staying away from the strikeout counts. This may mean being less choosy early in the count. Remember, the object is to get the ball in play! If the hitter decides that the pitcher cannot, in his mind, strike him out, then he can be more patient early in the count.
Evaluate the Situation. Although we will talk about situational hitting in another chapter, it is worth noting that each at bat has different goals. When the infield is playing back with a man on third and less than two outs, the hitter's goals are different from those he would have when hitting with the bases empty. The batter must hit to the situation; he must know what he wants to do in each at bat.
Be Fearless. To be a good hitter, the player must deal with the fear of being hit by the pitch. A person standing 60 feet, 6 inches away from him is about to throw a very hard object in his direction. It is natural to have fear, but the hitter must uncover and address this fear. The hitter must reach a point where he simply says, "I'd rather get hit by the ball than strike out or buckle my knees on a curveball that is approaching me."
Review the Strike Zone. When the hitter starts to struggle, the strike zone usually appears bigger than it is. The outside corner looks to be almost unreachable. In like manner, the ball also appears smaller. The hitter would do well to revisualize the strike zone. An effective method is to tape the boundaries of the player's strike zone on a wall. Every umpire is different, but the strike zone for a six-foot hitter should be approximately 18 inches wide and three to four feet high, depending on his stance. The hitter stands in front of the wall and visualizes and practices his swing at each area of the strike zone.
Work the Count. Simply put, the batter must make the pitcher throw strikes. A base on balls has a 100 percent on-base average! The hitter should not help the pitcher by swinging at balls out of the strike zone. The success ratio for a hitter over a full season often relates directly to the count when he hits the ball. Researchers, coaches, and players find this result every year when they look at batting outcomes in relationship to the count. When pitchers are ahead in the count (1-2, 0-2), the batting average will normally be 150 to 200 points lower than it is when the hitter is ahead in the count (3-1, 2-0). The critical counts, the 0-0 and 1-1 counts, swing the success-failure rate farther than any other count. In short, swinging at balls out of the strike zone can greatly increase the success ratio for the pitcher.