I've been following this thread and have read Swartz's
article. I'm frustrated because I don't really see the need
for the deep analysis that I see being put into this
question.
The so-called "Work-Kinetic Energy Theorem" is simply the
result of combining the kinematic equation
a*x =( vf^2)/2 -(vi^2)/2
and Newton's 2nd Law
F_net = m*a
which gives
F_net * x = 1/2 m vf^2 - 1/2 m vi^2.
Now if you want to stand on your head and say a prayer to
the Sun God that "The Net Work done is numerically equal to
the change in Kinetic Energy", I guess your welcome to do
it, but in fact the equation is simply an application of
basic kinematics and Newton's Laws.
Energy is a wonderful shortcut to solving problems through
the use of scalars instead of vectors - but it's not an
object of worship.