balk towards 2nd base

[WillSun]

I don't have my rulebook in front of me, and Dixie's website is very limited. I'm just going by my own experiences. I've never seen a balk to second either, it's just hypothetical.
They have been calling balk like crazy this season, and I guess I'm just confused on the issue. My understanding is that the pitcher must pitch from the stretch when there are baserunners, and once he is set, he must pitch or throw to a base, unless he steps off the rubber, in which case he can fake a throw... Now if this is wrong, I'm even more confused....