Interesting post, Rick.
I have experienced similar situations. Sometimes the fish just LOVE that reddish-orange boa yarn leech! I think the ones I tie are from the red/orange portions of the "Tweety Bird" color Bernat Boa yarn. That yarn also has yellow in it, but the yellow works fine all by itself most of the time.
I wonder if a red or orange marabou leech would have worked? Sounds like it was mostly an issue of color. But if they were striking short, as you mentioned, the boa yarn leech probably has a shorter tail than a marabou leech would.