It doesn't. Sortition is more like random sampling of the overall population. The assumption is that those being sampled are already "qualified," since Athenian citizens only make up the top 10% of the population. And, anybody who gets picked usually has some kind of qualifying process after the lottery. Additionally, it is typically used for large bodies (like members of a legislature) rather than a single office (like a President.) This limits the damage any one single individual can make.
I don't think the ancient Greeks believe in "Long Term Planning" in the way we believe it today. For that, you would have to believe in the "future" and "progress".
It's an interesting idea, but I think the more important part is ensuring that the candidates are qualified. Of course whoever decides on who's qualified or not will have a lot of power over the process. There needs to be some sort of objective measure to determine that, and that's going to be hard, and constantly subject to attempts to allow or ban popular controversial candidates.
Personally I've been thinking if maybe it would be a good idea if everybody could both vote for someone, and against someone else. That way, the most controversial candidates would never be able to win. Athens had a slightly harsher system where people would vote to banish anyone who was deemed to have become too powerful.
On the other hand, if the system is too moderating, it could become too conservative and it might become impossible to change the system once it's on a certain course; any popular newcomer who wants to address certain problems in the system would immediately be blocked by everybody who benefits from those problems.
I feel this could work if the "random rulers" would only work as administrators, legally required to follow a long term political plan that has been defined democratically with the population. I believe in both the future and progress, so a long term plan is required to me. Look at China and what they're accomplishing with their 2035 plan. I whish my country's politicians could think at least 15 years in the future when they legislate.
I don't think the ancient Greeks believe in "Long Term Planning" in the way we believe it today. For that, you would have to believe in the "future" and "progress".