I saw it here on HN, from someone else and I remembered these quotes:
1) Just because it can be turned into a number, doesn't it mean that it should be.
2) Just because something has already been turned into o a number it doesn't mean it is important.
Usually managers will want to turn everything into a number. Number of tickets closed per iteration cycles, numbe of issues opened, number of lines written, number of comments per number of lines and so on.
Because they think those give them a deep insight into the team dynamics, and it makes their job more justifiable because they can use those "statistics" and present them to their manager instead of say wave their hands and say "yap it's fine, we shipped this feature, found some bugs, fixed them".