In football, successful defenders can be a nightmare for [gambling] statisticians. During his playing years for Milan and Italy, Paolo Maldini averaged one tackle every other game. It wasn’t because he was a lazy player; it was because he didn’t need to make many tackles. He held back the opposition by getting into the right positions. If a defender makes fewer tackles, it doesn’t always mean he’s getting worse. It could mean that he’s improving.
Adam Kucharski The Perfect Bet p103