"Extension Isn't The Answer"
My problem with extension is that it does not happen the way it is being taught to many of our young players. What I mean is, in a high-level hitter, extension is ACTUALLY the "release" of the barrel, not the act of extending the arms.
Hitters are usually taught to "push" or "punch" through the contact of the ball. The problem is that pushing or activating the arms, will dramatically decrease the speed of the bat and encourage straight arms at contact, or 'Power V' position. Let's assume the hitter moves properly into his front side during his load, and his hands stay up and back while he's slotting the bat.
If the hitter's arms engage AT the ball and actively "extend" in the attempt to get to "extension," the connection between the batter's power (body movement and turn) and the barrel is disconnected. This 'bench pressing' of the barrel, instantly sucks all the power out of the swing.