Well 2 main things.
1. Personal experience (B3 experience).
2. I've seen the players of many B3 winning teams, and their SB was almost always quite low (compared to other skills).
I know there is a tendency to make people think that SB is important, but right now, I think it's not. If it was, there wouldn't be so much doubt over it. It would have been clear, after 22 seasons, that SB is important. Don't you think so?