balk

[Jerry]

It's also possible, Coach, that the ump(s) thought your pitcher made some motion with his hands . . . as if to pitch . . . before stepping properly off the back of the rubber or before stepping directly to the base to which he's feinting or throwing. I saw that a lot this year; the pitcher's in set and starts bringing his arms up at about the same time he's stepping off. Takes a little discipline to get the motion right, so as not to balk.

Since it's been called more than once on you, I suspect there's something wrong with what sequence was taught to your players.