Is this the normal "parked" position of the windshield wipers on a B738?
Took a look at several photos of 737-800s.
The windshield wipers are not in the stowed position. So they were in operation during the approach and were in this position when electrical power was lost, likely at impact with the sea surface.
Because wipers are never operated on a dry windshield, (everyone who flies knows this) and because these guys fly in this environment all the time and likely use the wipers frequently for tropical showers etc., their use indicates that there was rain on final approach.
The recorders will tell us when they started and what comments were made. We could posit an entirely-routine approach to a familiar airport in rain showers which went wrong very quickly.
PJ2