I've had passives with a crossover that high on the tweeters and like 2000 on the midbass. I think it was a 6db slope. I think they did it that way cause the tweeters were really effecient and it ended up being acoustically crossed at 3200. It was a cheap effective way to make the 2 drivers work together.

I realized this when I first went active. I opened up and drew a schematic of the crossovers and tried to mimic them, I was really confused like you are.

I ended up finding on the manufacturer's site that they were crossed at 3200 so I went from there.

Try and find some specs on the drivers your using. Even if you can only find fs that's a start.