now that you mention it, does the current between Cuba and Florida keep flowing in one direction, for hours on end, independent of tides ?
I think it’s relatively constant over the time scale of two days, and isn’t affected much by tides. Here’s an animation of a short-term forecast of surface current speeds for the Loop Current.
It’d be interesting to find data on the 2 days she actually swam. The currents, on just a visual glance, aren’t great corroborating evidence for Nyad. The top scale is only 0.8 m/s (though I’m not sure if the scale just means >=0.8 m/s or if 0.8 m/s is the actual top speed shown). And the really fast current is very close to Florida, while Nyad went quickest in the middle of her swim. From this data it appears she would have spend the most time in currents of only around ~0.5 m/s.
Tough to say. The data is neither a smoking gun nor proof of honestly.