It is very easy to get into the habit of pulling off the ball. This is especially true for power hitters. Have you ever seen a power hitter hit a home run and thereafter, he can't couch the ball? What happened? The home run took him out of himself. So as he pivots, he is also pivoting his head.
First of all, hitters should never take a 100% stroke. Doing this invites pulling off the ball. For efficiency, the stroke should be no more than 95%, saving 5% for command. As coaches, we sometimes go too far in the other direction by telling them to "just meet the ball." And now they start to aim the bat, which is not good either.
Hitting is a controlled explosion. Continue to be aggressive, with a 95% stroke. So what do we advise? The hitter is pulling off because he's rotating his complete body when he hits. He must focus on his head rotating in the opposite direction to the hips. As the hips rotate to the pitcher, the head should rotate to the ball.
Here are three baseball hitting drills for this:
DRILL # 1
Place a pile-on or glove across from the hitter just outside the batter's box in front of home plate (45% angle). After the hitter makes contact, he looks into the pile-on area. This keeps the head inside.
DRILL # 2 (with pitching machine or live pitcher)
Hitter assumes his stance, with no bat. To simulate holding a bat, his top hand grabs the thumb of his bottom hand. Coach stands in back of the hitter and holds his head on both sides. The hitter takes batless strokes at the pitched ball, while coach restricts the head to keep it on the ball as it enters the hit zone.
DRILL # 3 (Full Take)
The hitter will coil, stride, and read the pitch to the catcher. This keeps the head independent and disciplines it to stay with the ball. Note: This head discipline should carry over to his regular hitting, in the "full take", a pitch that is an obvious ball.
Coaching Points. The hitter should not go to the point where his head is pushing against the back shoulder. This locks up the back shoulder and restricts his extension. The head swivels. It should never tilt while reading the pitch. This causes the body to tilt also and the eyes to look on a vertical plane. Eyes must stay basically horizontal for best vision and body control.