User blog comment:FairyRaven/Fairy Tail Chapter 337: The Golden Plains, Review and Commentary/@comment-77.195.192.48-20130628095305/@comment-7418318-20130628100409

I'm starting to wonder if maybe Mavis (or someone else?) had a hand in bringing the Dragons into the present as a means to train the Dragon Slayers for the final confrontation with Acnologia.

But seeing how the Dragons got the better of the DS, that person arranged for a way to get rid of the Dragons.

That might explain at least a few of the incredible chains of coincidences, like the journal turning up at exactly the point where P-Lucy landed and containing knowledge that F-Lucy couldn't have had in a readable handwriting that F-Lucy couldn't have written.