The single frags doesn't mean anything. I didn't get my one during my first SR run. Pulled Madara at 1170, no SR frag of either. KCM Naruto was another 1080 for me. I did get a KCM single frag during that run. Seems to be mostly random-ish. Heard some people get whoever they got a single of, also heard from others than they got the opposite. So the single frag seems to hold no weight. It's just a random freebie as far as I can tell.