MIB or Jacob (As Christian) Told Locke he had to move the island. Moving the island caused the time flashes. The time flashes led Sawyer's team back to pre-1867 where Sawyer was hanging onto the rope sticking out of the ground. Someone will find that rope and build the well.
This is evidence of the first change made to the timeline.
Could this be the beginning of MIB's loophole?