According to the author of the book, this verse is about God helping Joshua find out who did something wrong by showing him one family at a time. In this story, they find out it was a man named Zabdi.
Joshua 7:17: And he brought the family of Judah; and he took the family of the Zarhites: and he brought the family of the Zarhites man by man; and Zabdi was taken:
This verse suggests that human plans are secondary to God's direction, which might contradict the implication of clan selection in Joshua 7:17 by human initiative.
Proverbs 16:9: A man's heart deviseth his way: but the LORD directeth his steps.