What year MLBUM do you have? I don't recall that being in mine (but I don't have it handy to check)
And, this points out the benefit of the "paper" books vs. the "electronic" books. If you had (only) the latter, you'd just do a search for the other topic you wanted and more than likely not find the answer to this pending question.
In this particular instance there is an implied "and that habitual motion is also no part of a motion to throw to a base." For example (and assuming no other motion; bases are occupied or there's a play, etc): 1) Pitcher in Set: Can throw to any base or the plate 2) Pitcher raises stride leg: Can throw to second, base being faced, or the plate. Cannot throw to the base "behind" him (1st for RH pitcher; 3td for LH pitcher) 3) Free foot goes behind the rubber: Can throw to second or the plate. Cannot throw to first or third. 4) Foot starts forward: Can throw to plate.
I went to officiating.com over the weekend and read a little bit in various forums (not all). I didn't see any "assholes". So, I'm wondering to whom some of the posts in this thread are referring?
I do see that it has a lot less "social" content than here -- and for me, that's a good thing. (I recognize that others have different opinions, and I appreciate that a lot of the social stuff is on specific forums I choose not to read here)
1. A runner is out when hit (a) by a fair ball, (b) in fair territory (with some non-relevant exceptions). That's not your hypothetical play. I will add that if the runner intentionally deflected the foul ball that had a chance of becoming fair, the runner is also out. Also not your hypothetical play.
2. Very few batters intentionally get hit in the head. At least not more than once.
I think most interps now have something akin to "maintain possession through the act of making the tag." Not quite the same as "voluntary release" but in the same vein. If it was all one action, then the runner is likely safe. If the fiedler was doing "something else" then the runner was likely out.