I dont get the comments being made about confusing the defenses...
Think HIGH SCHOOL FOOTBALL. You study game film, you look at your defensive scouting each week ( usually ours consisted of a picture of the player, position, and few comments about him such as: good arm, mobile Qb. or Strong runner, doesnt cut much. etc) If High school players can remember people by thier numbers and not be confused, I have a hard time believing professional athletes ESPECIALLY with as much film as they watch,would have any trouble at all with the number rule changing