All the talk today on sports talk about the Lions v Cowboys and no show I listened to mentioned this point. It seems this play was like the messed up coin flip where the ref did not understand what was said. The lions did cause some of the confusion so they aren't blameless. Seems the simple solution is just like the coin toss solution. When the normally ineligible player reports, the ref must announce it just like a penalty over his microphone, so everyone knows and can confirm he heard right before the play. I know I have heard it in the background of the game at times. So instead of walking to the defense, just turn on the mike look at the camera and make the announcement of the eligible OL. This way if he misheard, it can be corrected before the play.