http://www.youtube.com/watch?v=JwogLVGtDa8 - Ted Williams - Put your cursor on the 25 second mark to see his loading mechanics.
http://www.youtube.com/watch?v=NAEeKhbj7kQ - Albert Belle - Need only watch the first 5 seconds of this infamous moment to see the swing itself.
http://www.baseballhalloffame.....jsp?playerId=118416 - Eddie Mathews - The video link is in the lower right corner of the page. Put your cursor on the 38 second mark and play it through as often as needed. As a note....if this is the dropping action you see in your son's swing then he is OK.....if not....you want to help him get through this flaw.
Jimmie Foxx -
http://www.baseballhalloffame.....jsp?playerId=114367 - 27 second mark.
http://www.baseballhalloffame.....jsp?playerId=121578 - Babe Ruth - 2 second mark or 37 second mark.
These are indeed hitters that drop their hands (trigger) before lifting them again to load. That could very well be what is seen in your son's swing. If so then no problem.
And any other type of dropping motion of the hands is probably causing some reduction of ability to hit at his peak.
In my opinion, connecting the bat to the side of the shoulder is indeed a great way to stop the dropping motion of the hands and knob while launching the barrel.
Have your son lift his shirt sleeve and put the bat to the skin of the shoulder so he can feel the bat should it begin to drop down early.
Best of luck and good pick up on your part. Great initiative to come on here and seek friendly advice.
Coach James