VMCa and VMCg - HELP

[spitfire747]

Not sure if this is the correct place for this question.. but here goes.

I have always believed VMCa to be a lower speed than VMCg from a performance and PoF point of view, due to the shorter moments between the landing gear and fin on the ground compared to the moment between the CG and the fin when in the air.
two other instructors from two reputible schools have agreed, but my instructor at my school and the notes I have say that VMCg is a lower speed than VMCa.....the explanation given being "VMCg has got to be lower cos your not in the air yet !!"
He also backed this up with a diagram from a text book....but i am not convinced.

Anybody know any better ??

Thanks in advance