I don't think about it too much.
I've only seen one presentation and read a couple articles and some commentary by a few recipients of treatment.
It looks and sounds like a combination facilitation techniques, primarily isometrics applied in a "weakened" joint position that limits range of motion/function, that results in some cases in some measure of improved function. To me it looks a helluva lot like PNF with its use of diagonals, isometrics, reversing direction, etc. (I saw Greg Roskopf's [sp] presentation from SWIS a few years back)
I know he's worked with Dr. Leahy (is everyone from Colorado?) and has a relationship with Velocity and some sports teams.
I'm sure it's as effective as any other system such as trigger point therapy, spray n stretch, ART, NMR, AIS, NDT, ATSM, accupuncture, PNF, HAT (Hartman Applied Therapy

) and plain old strength training. If people get better, then I guess it's useful. Just another tool in the tool box so to speak.
Bill