WSOP 'migrating' to different time of year?

[DonkeyChip]

Two years ago the WSOP ME was in late May IIRC. This year it was in early July and next year it's scheduled in late July/early August. I would think there is a reason the WSOP keeps getting pushed later into the calendar year but I have no idea what it is. I don't know if future WSOPs will be pushed further into the calendar year or if there is some 'ideal' time they're shooting for. Any guesses?