The 2008 Picher tornado has been discussed in this thread before, but I'm gonna bring it up again...
First off, I do
not think EF4 is egregious and fully understand why that rating was assigned - most or all of the homes it encountered were unanchored, or poorly anchored at best. However, even ignoring the "well, by probability alone it must have encountered at least ONE well-anchored home" argument, for me personally Picher is a case of "if the shoe fits, wear it" as far as potential EF5 ratings go. I base this on the fact that the tornado actually managed to crack and scour part of a home's slab foundation. The slab was poured rather thinly though, so that is a consideration, but it's still extremely impressive when you consider all the other high-end contextual damage this tornado did. Normally I wouldn't consider a poorly anchored home to be eligible for an EF5 rating, but since the
slab itself was damaged, calling it EF5 at least makes sense imo.