What do you mean 'push his front bicep away from his torso'? Bregman photo below of a homerun has the same separation, or 'lack of connection' as you call it.View attachment 19706
Like most instructors, he fixes one thing only by breaking another.
He 'fixed' the bat drag by introducing a giant disconnect - the kid must push his front bicep away from his torso.
This is exactly what the Batspeed.com PerfectConnextion gadget does here:
I pointed this out when this gadget came out years ago.
And he still didn't fix the initial cause which is opening his hips during the stride.
Not to mention, this drill will more than likely not translate to a good game swing. What happens when he opens his hips and his rear forearm drops during a game swing?
In your model swing do you want the front bicep pegged to the chest? Isn't that arm bar?The only way for the back arm to hold form and not drag is to start farther away from the shoulder, right? I just dont feel right trying to keep the bicep pinned to the pectoral and keeping everything together.