Balk perhaps?

[Gee]

They called Louis Tiant's stop a "stutter stop" as he changed the direction of his glove four or five times while going from his chin to his waist and then came to an "obvious and descernable" stop which is now required.

I don't think they outlawed the stutter stop, they just said that the up and down movement is not not an obvious and descernable stop.

I have not seen a pitcher use that mechanic but if I did I would have nothing, providing he came to an obvious and descernable stop after stuttering his way down. G.