First time posting.
I read the first two pages and the last page so apologies if someone made this point already.
Like most (maybe, Im in Germany now, so I watched live) when I watched, didn't even notice the DQable offense. It wasn't until after the second heat did the broadcast say the US was DQed and showed a wide angle replay that I still didn't even see closely. Then I eventually rewound the feed and saw it all, and for a few hours and texting with people about it. Questioning what I just watched, what she was thinking, how she didn't see all other 7 teams lined up 20+ meters behind her.
Lets say they were using a short leg approach for Irby (which is tactically smart (M/F)) and Irby goes to a meet official and says "hey, where does the exchange zone end?" and the meet official points at the 2-turn stagger, and she backs up 3m off of it thinking she's right where she's suppose to be. Except that 2-turn stagger is 4m past the end of the exchange zone. If this is what happened, seems like not her fault.
To the person who questioned why the 3rd and 4th leg runners were not also short legged in their start position, because on a F-F exchange (2nd to 3rd) you might as well be even and safe. And for a F-M exchange (3rd to 4th) you want to male running 410m, so as early as possible. So both at the beginning of the regular 4x4 exchange.
Maybe it was an innocent mistake by a race official (most likely), but mostest likely it was a combination of multiplying a meet official, a 20 year old, and a dumb RELAY COACH trying to concoct some stupid scheme to what? win by 4 seconds instead of 3.5 seconds.