Actually @grayhawk did not give such an example. (And that's no dig at Grayhawk.) Grayhawk's suggested mechanic was actually taught in 1997 at umpire school (and, in fact, it continues to be taught). So, Grayhaw's post is a compelling example of an amateur umpire knowing and using an advance mechanic taught at pro school that a lot of pro school students struggle with. (I would expect nothing less from @grayhawk, BTW).
Unrelated to the quoted posted above, but related to other posts in this thread, I'm going to stick up for some of us trainers. By way of example, I actually received a text this afternoon from one of my high school umpires. I have been the lead trainer in my high school association for 15-years, and this umpire texted me stating that he is at a college 2-man camp as he is trying to advance in his career and get onto a Division 2 college conference staff. He texted me and wrote, in part, "I want to thank you...I am at the 2-man camp this weekend and they are running the same drills you do. And I nailed my double play footwork. (Your) camp puts guys ready to work at any level. I got the best base evaluation I have ever received and it is from (your camp)."
Honestly, that is the highlight of my 2020 umpire year. Just sharing to say that not all trainers are in it to be d!cks, nor an overlord; some of us really do want to make each student the best they possibly can be.