Right handed pitcher normally sets up to pitch from the stretch with right foot as pivot foot in contact with the rubber. With runner on first, pitcher goes to stretch position with left foot as pivot foot, now facing 1st base. Pitcher steps toward 1st to pick off R1, in a manner that would not be a balk for a lefty. By coming to the left handers stretch, in contact with the rubber, is this a balk?

yes

oops. references - FED2-28-6 - "The pitcher's pivot foot is that foot with which the pitcher contacts the pitcher's plate when he delivers the ball. For example, the pivot foot is the left foot for a left handed pitcher (6-1-1)."

Pro2.00 - "The pitcher's pivot foot is that foot which is in contact with the pitcher's plate as he delivers the ball."

Dig out the book(s)!

Also, for FED, see 6.1.3L -- it's the very play being discussed here.

This is Babe Ruth, not Fed, sorry. I know the ruling has to do with the pivot foot. OBR defines PIVOT FOOT as "the foot which is in contact with the pitchers plate as he delivers the pitch". He is doing this strictly to pick off the runner and while I know this pitcher can not deliver the pitch well, with his right arm toward the batter, but I suppose he could?. It is not a question of how he disengages or how he attempts the pick off, bottom line does he balk when he assumes this backwards stretch?

I think this would be ok if he faces the the batter as a left handed pitcher
 

If he faces this new batter as a left handed pitcher, I think it would not be a balk.(FED 6.1.1.Note, page 37)

Greg

I wouldn't call it a balk assuming he's done everything correctly. I would hope that R1 has taken note that the pitcher is now looking dead at him.

However, NAPBL has a paragraph about "ambidextrous pitchers" which could be applied to prevent this sort of shanagan.

6.14 AMBIDEXTROUS PITCHERS
In the rare occasion of an ambidextrous pitcher the pitcher and batter may each change positions one time per at-bat. For example, if the pitcher changes from right-handed to left-handed and the batter then changes batter's boxes, each player must remain that way for the duration of that at bat (unless the offensive team substitutes a pinch hitter, and then each player may again "switch" one time).

So if the pitcher started out as right handed, then switched to a left handed position to try for a pickoff, by the direction given above, he's now stuck as a lefty. Now let's see him pitch to the batter :).

Jerry

In the Baseball Canada rules, there is a provision in the book that suggests this could be called a balk.

8.05 If there is a runner or runners, it is a balk when-
(h) The pitcher unnecessarily delays the game.

In my opinion, setiing up as a left hander is an unnecessary delay unless the pitcher can show me that he will at some time throw as a southpaw. If he can't demonstrate to me that he has intentions to make a pitch as a leftie, he's slowing my game down and I'll call him on it.

If he puts his glove on his right hand, he can pitch left handed to the batter and so engage the rubber that way. Once he begins a batter as a left hander, he would be required to pitch to that batter left handed. 6-1-1 Note. FED. OBR has a similar ruling.

I would call the balk, if the pitcher protested, I would give him the option to pitch to the batter left-handed.