We should approach defenders a bit differently than we approach our attacking options. Since a large part of how defenders score points for us in fantasy is collecting clean sheets, we essentially can just compare which teams are likely to collect clean sheets. Though we are definitely selecting individual players for our defenders, we are also selecting defensive units. If I want to choose Corey Ashe, I am effectively buying into the Houston defensive unit as a whole. Because of this, I tend to choose the cheapest option in each unit who will be a starter unless there is reason to believe one of the more expensive players will produce more bonus points or goals/assists.