Why does the NFL take almost 2 weeks to let everybody know that a play was illegal?

He was eligible. He was on the end of the line and declared himself as eligible. The issue, as I understand it, is that a player who was eligible on the previous play moved to an ineligible position, which is an illegal substitution. He is supposed to leave the game for a play.

I don't know what the big deal with all of these formations is, honestly. The guys on the end of the line, and everyone behind the line of scrimmage, are eligible. Cover those guys. Pros should be able to handle this.

Mr K is right. He was eligible. Even Pop Warner players should know to cover the end no matter what number he's wearing.