I've read that thread several times. I get lost in some of the technical talk. For infield throws I'm teaching my dd to throw like the fagan pic. Once the hands seperate the throwing forearm is pretty much parallel to the ground with ball about chest high. Then step some hip rotation and throw. But it would very hard to explain without showing..
I haven't really figured out how to explain it without getting technical, so I mostly resort to demonstrations. My DD had elbow and shoulder pain from the the wrist flicks and 90 degree L position. She then slipped into sidearm. It took awhile and Austin Wasserman's Arm Behind Drill really got her to feel the correct sequence, which in turn has allowed her throw further without pain. Now she will do that drill while just playing catch.