"Here is the rule for a pick off move for a lefty pitcher. If the pitcher does not follow this rule, then it is called a balk. First, when the pitcher starts his motion and his right foot crosses his left knee, the pitcher has to throw home. If he tries coming to first he will be called for a balk. Some pitchers will cross over their right knee but not cross their right foot, this can sometimes confuse a base runner, and he can pick over to first base without a balk being called. An imaginary 45 degree line goes from the pitching rubber to in between home plate and 1st base exists. If you are pitching the ball home you must land your right foot on the home plate side of this imaginary line. If you are throwing over to 1st base your right foot must land on the 1st base side of this imaginary line."

Have another look at Julio's pick off, and try telling me it's a balk. His right foot stays behind his knee, his right foot is on the first base side of the 45 degree line. I think it's a textbook definition of a non-balk.

http://m.mlb.com/video/topic/63817564/v1206079383/lad-wsh-gm5-urias-picks-off-harper-to-end-the-5th