[JTillery]

"Plus, isn't the head drop just a consequence of starting the DS with a lower body/hips move, which moves the left hip nearer the target, weight more on left foot/leg, and with intention of keeping the upper body cog or head somewhat fixed, your head has to move down or spine tilt away from target, hence move your head down?"

This is a good observation. Tigers grip was strengthened, and having a strong and level left wrist is an awkward combo if you haven't tried it. Im not endorsing this theory necessarily, but there is no point of setting the radius via the level left wrist if you have no intention of maintaining that radius, or especially, if you plan to hold the face....then you need it for support. Is that the best plan? who knows, certainly not our LBG way or Homer's way, but that's the defense.
Secondly, Brian is right here....it's impossible for your head not to go down if you shift weight totally to your left leg via hip slide while maintaining a centered head. The more centered the player and less the "leaner" the less you'll see it. (Nicklaus/Gay vs. Nelson/Trevino/D.Johnson). Like it or hate it, the vertical adds snap. Consistent??? Make your own decision, but it's happening everywhere. No one told them to do it until maybe recently. We could put pictures up all day of guy's heads going down then up, down then staying there with lean, barely down and barely up. Hundreds and hundreds of victories and millions and millions of dollars also........kind of hard to call it wrong. In line with TGM, no. Ideal for consistency? you tell me.....but outright wrong?????? Would the other make them better, or would it have made them people you've never heard of? Don't know