1984 was by far the worst. The Cubs had a great team, it was stacked on offense, 6 guys with 80 or more RBI, a nice blend of speed, power, and OBP. A deep pitching staff and a lock down closer. They lost to a flakey Padres team that laid down like the dogs they were once they got to the WS against Detroit. That was the biggest pain I've felt as a Cubs fan. Although 2003 hurt, but that team had a very shaky bullpen, so I don't know that they really underachieved when it was all said and done. In '89 and '98 they just lost to far superior teams. This year, was an inconsistent team with 85 wins and a lot of holes.