I'd say from what you posted that the problem is setting too hard. All you have to on a fly rod for brim, trout, crappie or anyother soft-mouthed fish is to raise the rod. You have to practice this in order overcome the habits learned fishing for bass. Fly lines are tough, leaders on the other hand are liable to snap. You can even snap one with to hard a down cast. Poppers are notably easy to break off because of the concave mouth of the lure. Remember, in fly fishing, it is practice, practice, practice. I usually use a 2 lb tippet for brim, perch and trout. It make for more of a challege. If you get into an area that has a lot of perch, you can get a lot of practice real quick. Tight lines buddy.