There are also some that teach people to start off with a tilt of so many degrees(at setup). Others advocate the HANDS MORE AT MID-BODY, AND THE SHOULDERS AS LEVEL AS POSSIBLE AT ADDRESS(Reverse K vs. Tripod).
Also... do you see a correlation between those that bend over more at setup(down the line view), with less axis tilt(face on view), and those that stand taller, with more tilt(Mac O'Grady vs. Davis Love)?
-B. The downward force results from the action of Axis Tilt (Hip Slide-7-14) and/or Uncocking left wrist (2-P) if there is any of either. Otherwise, the Lever Assemblies are dropped, pulled or pushed downward from their fulcrums (6-A).