>>> What is the proper fix for a hitter who is pulling his bat out of the zone too quickly? It almost seems that he's trying to pull everything down the left field line. If he doesn't get an inside pitch, the result is a week pop up to the right side of the infield. He does have a lot of power with the inside pitch. <<<
I have seen the problem you describe in the swing of many young hitters. They have little power to the opposite field and most of their best-hit balls are pulled foul. One of the Dads of a recent Swing Review I analyzed, stated that if the foul-line was just swung around another 30 degrees, his son would have hit over 600 and led the league in home runs.
"Pulling off the ball," or constantly pulling pitches with little power to the opposite field are all indicators of "bat-drag." Bat-drag occurs when the angular acceleration of the bat-head does not keep pace (or stay in sync with) the advancement of the hands. The batter's mechanics extends the hands to the contact zone, but leaves the bat-head dragging 30+ degrees from contact. Good bat speed is not attained until the bat has passed through the optimum contact area. And, by the time the bat-head does arrive, the hands are now arcing around toward the shortstop - thus, pulling the meat of the bat off the ball - especially on outside pitches.
The bat-head travels about 180 degrees from the launch position around to contact - about 90 degrees back to the lag position and then another 90 degrees on to contact (perpendicular). When the batter extends the hands during initiation, he accelerates the knob but the bat-head just slides over to the lag position and trails behind the hands well into the swing. There is no way a batter can attain good bat speed in the optimum contact zone with a static bat at the lag position.
In order for a batter to attain maximum bat speed in the optimum contact zone, his mechanics must accelerate the bat-head around the entire swing plane (180 degrees). This means that from his launch position, he must first accelerate the bat-head rearward to (and through) the lag position and then around to contact. This cannot happen if the batter initiates the swing by extending the hands forward.
It may be helpful to understand what I am talking about by studying the video clips below.
No Whip Effect From "A to B" Hand-Path
Overhead of CHP
Note: Rose does not extend his hands at the pitcher. They are first directed more perpendicular to the path of the in-coming ball.