I think what happened was that he had built up such resentment among writers that in the early years of his candidacy he was the victim of a certain amount of retribution. As years went on, offensive numbers became more and more bloated (mainly due to roids) and that diminished some of Rice's accomplishments. In the last few years (almost 20 years removed from his playing career) there weren't very many writers who covered him and had the opportunity to judge him first hand. They only had the numbers and the stats, and the stats were diminished by the decade of roids.
Mattingly was a great hitter and fielder. I haven't done an analysis of their stats, but regardless of stats Mattingly didn't dominate like Rice did. Rice just flat out scared the hell out of pitchers. Yankee fans hated to see him in the batters box. He dominated in a batting order that had Evans, Lynn, Yaz George Scott, Fisk. Each of them were major offensive forces, but it was Rice who made the opponents sweat.