wind up approach

Question
Dennis, I've been teaching my son (14) the no wind up pitching style. Where he places his pivot foot on the rubber and the free foot behind.From there he brings his free foot forward without lifting it and delivers the pitch. Last night after going three up and three down in the first inning the next time he came to pitch the ump said what he was doing was illegal that he had to start with both feet on the rubber then take a step back then go into a traditional pitch. Was the ump correct? Please help.

Answer
Hey Jerry,

I don't totally understand..
Pivot foot on the rubber and the free foot behind?
The free foot should be in front of the foot that is on the rubber.
Then he is to stride toward the plate.
No umpire could call this wrong...

What he probably meant was:

Start with both feed perpendicular to home plate. One foot in FRONT of the rubber, and the other BEHIND the rubber, neither touching the rubber.. Your 14 year old must put his pivot foot on the rubber first. Then proceed doing what he was doing..
The umpire did not want him to do it backwards by planting his free foot first.
Remember pivot foot on the rubber first. Then he'll be okay with all umpires.
Dennis