That is exactly what happens in the Gulf. Although, as I'm sure you know, you are never in the Gulf Stream in that area of the Gulf.
And as you approach the Keys from the Gulf side it gets very shallow well offshore of the Keys.

I'm not sure who's local knowledge Skip was relying on but I bet if they real had made 200 deliveries to that area and known it was going to be blowing 20-30 with 6-8 foot seas with a 6 1/2 draft vessel, they would have told them to go to Key West and not try to get in Marathon in those conditions. If they had to go.

The distance to Key West from the Tampa Bay sea buoy is in fact a few miles less (as the crow flies) than if you go to Vaca Key (Marathon). And the entrance to Key West in bad weather out of the North is much better than Marathon to say the least.

Of course going to Key West adds distance to your trip to the Bahamas. But at least you are going with the Gulf Stream on your way up and over.