Linear writes...It's impossible to execute a high level swing with a towel being held in the lead arm armpit.
The lead arm (upper arm) must be perpendicular to the spine for maximum rotational efficiency and swing quickness""
It is NOT impossible to begin a high level swing there. Thats is what you don't see. Getting the bat out of plane on purpose forces the hands to move back , the bat to flatten, as you launch and is what increases torque and bat speed through hips shoulder separation. Why doesn't the pitcher just start with this hand back in the throwing position , turn and throw. What is the purpose of over lapping the upperbody take away and the lower body hips rotation to the plate
Starting on the 45 works for some and for some they are actually too quick to the ball and tug the knob. It is hard to project the barrel from there. You also have a tendency to start early and more difficulty with offspeed.
Again see Babe Ruth, Bo Jackson, Chipper, Kirby Puckett, Piazza, Giambi,Glaus. If you look close many start on 45, lower the lead elbow, cocking and making the bat go out of plane toward vertical and return to the 45 slot( as always ) at launch. Their hips **** , shoulders load, bat knob comes out toward oppo batter box, the barrel is perp to to ball flight.
If you have a kid that is not performing up to par just let them try it. It takes one minute to switch back.