I've got 8,103 Cubs cards from 42 different brands listed on a spreadsheet. A random number generator picked five cards, one each from the past several decades.
1950s / 1960s: Topps 1957 #137 Bob Rush The righty spent ten years with the Cubs; 1957 would be his last year. After winning 13 games in each of the last three seasons, Rush fell on hard times in 1957, dropping to a 6-16 record with an ERA of 4.38. Not surprisingly, the Cubs traded him after the season.
1970s: Topps 1978 #76 Steve Ontiveros I liked the way this card looked, with Ontiveros in the home pinstripes, more than I liked the player. After Santo and Madlock, Ontiveros was quite a step down at third base. Injuries limited his playing time in 1978 to only 82 games.
1980s: Fleer 1984 #497 Carmelo Martinez Martinez didn't play for the Cubs in 1984. He was part of a three team swap between the Cubs, Padres, and Expos. The Cubs ended up with Scott Sanderson while Martinez landed in San Diego. He played in all five games of the NLCS against the '84 Cubs, but hit only .176. Too bad Steve Garvey didn't do the same!
1990s: Fleer 1998 #563 Kerry Wood What can I say about Kerry Wood's 1998 season! 20 K's on May 6, 13-6 record, NL Rookie of the Year, and a late season injury.
2000s: Topps Factory Team Set #CHC3 Greg Maddux This card is from Topps' first year of the 14 card team set and was identical to the base set card. By now 40 years old, 2006 would be his final season with the Cubs. He was only 9-11 with an un-Maddux-like ERA of 4.69 before being traded to the Dodgers at the trade deadline. He rebounded nicely in LA, going 6-3 and posting an ERA of 3.30.