In 25 words . . .

[bossman72]

It's really not deceiving to the baserunner. All base runners are taught to watch the pivot foot of a RHP at first base. When the pivot foot moves, they go back.

I mean, if they allow a jump turn (where the pivot foot also moves toward third base), why would the jab step not be legal as well?

This move has been legal for a very long time. Don't try to be a crusader against it since it's not EXACTLY by the book. I guarantee if you don't balk this you will not hear a peep from either dugout all game. If you do balk it... well... good luck

[socalblue1]

In all rule interpretations I am aware off, the jab step is considered the same as a jump spin.

So long as the free foot gains distance and direction no balk. As with the jump spin, need to watch out for F1 simply pivoting on his free foot while bringing the pivot foot forward and/or toward 3B.