Just a short addendum:
One detail I neglected to mention, in my first report, was that I was suffering from a blister on the top right side of my left index finger, after a long practice session Sunday at a nearby pitching/chipping green. I was having trouble holding my interlocking grip together -- so I told my cousin, as we walked from the fourth green to the fifth tee, that I might try modifying my grip.
I hit the tee shot (smother pull) with a modified baseball grip (10-finger, with left thumb down shaft).
And then, of course, KABOOM! Right on the noggin.
Yesterday, when I mentioned to my cousin that I had, in fact, hit the most recent drive of my life with a baseball grip, he told me that the one time Lee Trevino tried a baseball grip was the same time he got hit by lightning.
Let this be a lesson to us all!
(The lesson: Don't practice so long that you get weird blisters.)