Lots of times these "leakers" will embed one nugget of truth in with a bunch of BS in order to pass off the BS stuff as being real as well. For instance, just a few weeks ago there was a leaker who knew the exact date that Nintendo would announce details for Switch's online service. However, several other things from his leak have since been proven untrue. For instance, he said the Sonic Racing game would be announced at Nintendo's E3 conference and would feature Sonic on foot with some other character in Karts, that part was confirmed fake today, as Sonic is in a kart just like the rest of the characters.
Didn't that guy state that he got lucky with the date himself afterwards though?