Can you move a readied unit from one controlled battlefield to another controlled battlefield, potentially leaving the first battlefield uncontrolled?

Ruling: You cannot move a readied unit between battlefields without a source of ganking. The ability to move units between battlefields requires ganking.

Nuances:

• In the observed game situation, the unit was moved via Windswept Heath, which grants units ganking
• Without ganking, units cannot move between battlefields even if you control both