[SanDiegoSteve]

Jim Evans says that the pitcher must break contact with the rubber with the pivot foot on the feint to 3rd on the 3rd to 1st move:

"On the "trick 3rd to 1st" move used by the righthander, the umpire should be especially alert for two criteria:
(1)
the pitcher may not break the back plane of the rubber with his free foot before attempting the feint to 3rd; and
(2)
in his feint to 3rd, he must break contact from the rubber with his pivot foot.
Breaking the plane would be a balk in violation of 8.01(a) and failure to break contact would be a balk in violation of 8.01(c)...not a direct step from the rubber ("while touching his plate")."

I don't see that in the rule 8.05(c) Case Book comments. It says you can't feint to third, and in practically the same motion, wheel and throw to first. It prohibits this because it is practically impossible to step directly to first. But it is possible to feint to third, in contact with the rubber, then maintain contact and step and throw to first. Two separate steps directly toward bases, yet not disengaging the runner.

I will do further research and come back later. I am more confused than I was yesterday, that's for sure.