Experience has taught me that many hitters fail to execute the Turn Phase when swinging at full speed.  There is a hurry to get the barrel around to the ball, causing the hitter to lead with the upper body and bring the hips around afterward, a flaw I call "hips trailing".  Be sure to execute phase 2 properly when swinging, and lead with the hip turn.

2.1 SHIFT WEIGHT, ELBOW TO HIP
The first movement of the swing is a shifting of the weight forward toward the ball.  It's important to shift most of your weight (70-80%) onto the front foot to enable your back hip to turn freely.  As you shift your weight toward the ball, the front heel will drop flat and the back heel should start to lift.  At the same time, bring the back elbow down toward the back hip pocket.  This is the last point in the swing where you can hold up; once the hips start to turn, it's difficult to stop the bat:

  • Drop the front heel and shift your weight forward onto the front foot.  Flex the front knee toward the ball and move your whole body forward
  • Drop the back elbow to the back hip as your weight shifts
  • Drop the bat barrel to a flatter position to get on the plane of the pitch, but stays back pointed behind the hitter’s back
  • Adjust your upper-body lean toward the plate depending on the height of the pitch: lean out from the waist more for lower pitches, less for higher ones (you can adjust in later positions as well)
  • Start to turn the back knee toward the front knee in preparation to firing the hips, and the back heel starts to lift slightly
  • Keep the front shoulder closed - do not turn the upper body

2.2 TURN THE HIPS
Once you have shifted weight onto the front foot:

  • Fire the back hip around toward the pitcher, rolling the back foot over onto the point, heel high. The turning motion is done by turning the back knee toward the front knee; it is NOT done by twisting the back foot or "squishing the bug."  The back foot should just roll over onto the point. 
  • As your hip turns, the back elbow rides on the back hip bringing your hands out from behind your body. 
  • As the hip turns, keep the front shoulder closed and the front elbow down. There's a tendency to turn the shoulders with the hips - don't.  Opening the front side too soon will cause the hitter to pull the bat off the ball.  Also, keeping the front shoulder closed will create a momentary twisting tension between the upper and lower body that you'll release during the next phase of the swing.  Lifting your front elbow (aka "the chicken wing") will cause the bat barrel to drop and put a loop into your swing.
  • Keep the elbows and wrists cocked - that is, do not start to rotate them yet.  We want to save those rotations to accelerate the barrel through the hitting zone in the next phase (Phase 3: Extend through the Hitting Zone).  If you rotate them now, you are surrendering up much of your power.
  • Vertically, the hands should move straight downhill along the shortest path to the ball as shown in the graphic below

Phase 2.  The Turn

Phil Plante's

The second phase of the swing is the Turn, and it is the first phase of the swing proper.  The starting position for the Turn phase is position 1.3, the Ready-to-Hit position, which the hitter attains at the end of the Pre-Swing.  The hitter then shifts his weight forward toward the ball, brings the back elbow toward the hip pocket, and turns the hips. 

The Turn is the rotational phase of the swing and involves a rotation of the lower body.  The upper body and arms stay relatively quiet and do not rotate much during this phase.  In the next phase (Phase 3), the hitter will release the upper body and arms.