Chicago Cubs: The 1998 pitching staff was an interesting mix.
In 1998 the team had some historic individual performances from rookie Kerry Wood and closer Rod Beck, who recorded 51 saves that year. The pitching staff as a whole however was mediocre at best. As a team they pitched to a 4.50 ERA (14th in MLB), 14.7 fWAR (15th in MLB) and top 10 in home runs given up (180).
They got 20+ starts from five guys and Wood was the only one with an ERA under 4.00. It included Steve Trachsel (4.46 ERA in 33 starts), Mark Clark (4.84 ERA in 33 starts), Kevin Tapani (4.85 ERA in 34 starts/35 games) and Geremi Gonzalez (5.32 ERA in 20 starts). As a whole the starters put up a 4.54 ERA and 4.26 FIP. Again these are pretty mediocre numbers and it is hard to win in the postseason with middle of the road pitching.
Worth mentioning bullpen numbers. The team had a 4.55 FIP which was the best in baseball. In addition to Beck it saw solid performances from Terry Mulholland (2.89 ERA) and Mark Pisciotta (4.09 ERA). That was about it. The bullpen was carried heavily by Beck, who ended up pitching 80 1/3 innings that year. When Beck got his 51st save in Game 163 he was pretty much gassed and barely threw 80 mph at the end of the year.