Ellofiend, controlling isn't just about learning a set of rules and facts. It's about being able to pull them all together as a coherent whole and applying them. So yes, it's very dependent on your pre-existing abilities and attributes. All you can do is give it your best shot and hope you demonstrate the attributes they're after that indicate you have an aptitude for controlling. The training is about moulding your raw skills into a suitable form. Yes, you have to also learn a lot of rules and facts along the way but ultimately you need to be able to demonstrate you can separate aircraft. That continues throughout your career.