There was a tornado in Yazoo City, MS like a year before the Superoutbreak of 2011. I believe it occurred on April 24, 2010 and was rated low-end EF4 which seemed reasonable given the damage it did in and around Yazoo City. It was huge like 1.75 miles wide and on the ground for nearly 150 miles. Do you suspect that tornado may have been capable of EF5 damage somewhere along its track?I agree that this one was probably a higher-end EF4 even though the DIs didn't quite get it that rating. Definitely in the same ball park as Holly Springs and Perryville.
The EF5 tornadoes on 4/27/2011 are pretty much in a league of their own when it comes to violence, to a point where most of the F5 tornadoes on 4/3/1974 almost look tame by comparison, but the EF4 tornadoes were unusually violent too. Personally I don't have much doubt that the Cullman/Arab tornado, the Tuscaloosa tornado, the Flat Rock tornado, the Rose Hill/Enterprise tornado, the Ohatchee/Piedmont tornado, the Ringgold tornado, and maybe the Dadeville tornado could have caused EF5 damage if they had hit more/better-constructed structures at their max strength.