When I first came to Negril in 2001 the beach in front of Boat Bar was at least 2-3 times wider than that (i'm trying to be very conservative in my estimate), and UPhill from the water! Since then I've seen it gone up to the bar, back partway to 2001, like you show for 2008, etc.
It is pretty impressive how the waves lick away the sand, spread it around along the sea edge and push it back ashore again.