I would say the tail was too sparse or too short maybe? It could also have something to do with the hook you are using as well.

In general, when I tie dries, when I'm done I will take the fly out of the vice and drop it on the table a few times from about 8" up or so. If the fly is balanced correctly I find they will land sitting wings up etc, balanced on the hackle and tail. The key is having the tail long enough and able to support the fly from the back while the hackle matches the hook gap reasonably so the fly sits correctly and the hook has enough weight to counter the materials properly.