Yeah, Mattingly's peak was great, but that was essentially his whole career. He'll inevitably get in on some Veteran's Committee or another, but guys like Will Clark or John Olerud matched him on peak, exceeded him on career value & also had postseason success to boot, but yeah, neither played for the Yanks or had to cut their sideburns that one time, so...
Mattingly 6YP: 147 OPS+ | 33.0 WAR (CAR: 127 OPS+ | 42.4 WAR)
W Clark 6YP: 152 OPS+ | 32.0 WAR (CAR: 137 OPS+ | 56.5 WAR)
Olerud 6YP: 136 OPS+ | 31.3 WAR (CAR: 129 OPS+ | 58.2 WAR)