Don Mattingly had 6 good seasons (years 2-7) and was average after that. He only had 4 seasons where his slugging was over .500. He was a dominant, impact player for his first few years in the league, but faded fast and hard, only average or below hitter for a 1B after that 6 year run. He averaged 40 doubles and 20 hrs a year for his career. He only played 14 years and if he wasn't a Yankee he would never have been considered for the HOF. We probably all agree Fred McGriff deserves to be in, but we certainly don't see the media pining for him like they do for Mattingly. Few consider Keith Hernandez, John Olerud, or even Kent Hrbek HOF'ers, but they had equally productive careers and very good peak seasons as well.