Not so much wrong as unsure of if my understanding of the rule was correct. As with many rules situations, there's a story behind this. Working with a rookie. R3, right handed pitcher. Takes a jab step to 3rd and doesn't throw, my partner calls balk. I echo his call. DC request time and goes and talks to my partner. He asked me to come over and says his foot was on top of the rubber. Told him he was right, pitcher was in contact with the rubber. Game ends, we look up the rule and all OBR says is "in contact with". I got home, started over thinking and thought that if its that easy, I may be misunderstanding. So I put it up here to ensure I wasn't missing any grey area and my understanding was correct.