Gulf of Mexico hurricanes seems to almost always exceed expectations.
It's that warm water that does it. They need to revise their models for Hurricanes that get into the Gulf.
In the case of Florence they ended up evacuating many more people than were necessary because they over estimated the power of the storm by at least two categories. That's not necessarily a bad thing, better to be safe than sorry.
In the case of Michael it's just the opposite, it looks like a lot of people won't have enough time to either evacuate or take care of their property because they under estimated the power of the storm. I was surprised to see how fast Michael ramped up to a 4, almost overnight.