Dear Mike,
Having the toe up in the air mis-aims the loft on the putter face to the inside, so there is a chronic bias to miss inside. Golfers can get used to this and still putt straight, but it's definitely not a good idea.
This may sound a little goofy, but have him putt on concrete or linoleum and see whether he can putt dead straight to a tiny target 20 feet or so away. If he can do that, then he has sorted out something temporarily serviceable for technique, and his current problems are more about distance control, reading and aiming the putter. Can he aim the putter face accurately? Does he have the ability to STOP the putted ball where he wants it to stop? These are basic skills.
Dropping the hands, in and of itself, is not bad if done naturally. He may really be "placing" his hands lower and closer to his thighs than they would naturally "drop" or "hang". Most of the times, human bodies have the hands "hanging" naturally in a putting setup (slightly bent forward over the feet) directly above the toes. Do his hands hang above his toes or closer in?
At his address setup, have him holding the putter his usual way, and then simply let the right (rear-side) hand swing free off the handle. If the hand swings ONLY sideways, then his hands are hanging naturally, and that's good. If the hands swing closer to his thighs, then the hands are too far away from his thighs at address. If the hands swing away from his thighs, the hands are too close in at address.
Once the hands are in a good hang for the setup, the LIE of the putter then depends upon where his face is aimed to the ground (not where he is "looking" at the ball -- that only comes after he sets his face). If he can aim his face straight at a point on the ground out from his feet about two putter heads out from his toes (and not closer than 8 inches), then that is pretty good. With this face posture and hands hang, he is ready to be fitted for a proper putter that will lie flat on the surface. Just imagine a line from his hands out to the spot he faces on the ground -- that is the shaft (at least for a center-shafted putter -- a heel-shafted putter hits the ground about two inches closer to the golfer than the spot the face aims at).
If you place you son in this posture without his putter, and then while he remains in this posture you see how his putter fits this situation, you may learn something.
If you change his putter, he may not be able to reproduce whatever adaptation he has learned for putting straight with his odd setup, and there will be a transition period where he adjusts to the new setup and putter.
Another "goofy" suggestion takes a bit of trouble. Get a stick about as long as a putter and "hinge" a putter head onto it -- just a flat piece of wood about 5 inches from hinge to toe, about 1 to 1.5 inches high, and whatever thickness you want. The putter head will hinge onto the stick just like a foot on a leg when the Achilles tendon has been severed (it'll droop toe-down when lifted off the ground). If you can concoct such a training device, then have him putt to a small target 20 feet away on a slick flat surface. This will train him to know that a putting stroke is a "sideways" stroke that always goes exactly sideways out of the setup. This training will make him dislike having the toe in the air, I believe.
Let me know what is going on.
Cheers!
Geoff Mangum's PuttingZone.com & PuttingZoneŠ Magazine.
http://puttingzone.com
Golf's most advanced and comprehensive putting instruction -- you're either in the PuttingZone, or not.
Over 1.4 million visits -- 100,000 monthly from 50+ countries -- and growing strong.
518 Woodlawn Ave
Greensboro NC USA 27401
011 (336) 340-9079 "cell in me pocket"
011 (336) 510-9662 "Vonage SoftPhone"
"geoffmangum" Skype
"puttmagic" AIM / Yahoo IM
geoff@puttingzone.com MSN IM
ICQ 277025051
geoff@puttingzone.com