Roots, I think I disagree with your hypothesis about calculations "going wrong" and VEM being 'subtle'.
I've been playing a lot of CTTH to fine tune my understanding of my RktBldz irons - you know - same distances, same elevations - just different winds. In 4 rounds at Celtic Manor today, on the 3rd hole with the same club (5I), hit within +/- 1 bar of the center marker, same amount of power (100%), slightly different amounts of "back spin" got the following net results :-4 yds, -1 yd, +20 yds, + 30 yds. The winds btb varied between 2 to 4 mph.
Now, I lasted a whole semester in Engineering at college 42 years ago, but there is nothing subtle about the ball traveling an extra 16 to 26 yards!
So I attributed those odd results to VEM and, on the 5th round, repeated the club, power, back spin & aim and came up1 yd short.
Subtle, I don't think so!
As for calculations "going wrong", maybe - but that thought must be keeping our astronauts awake at night!