Mike "King" Kelly was considered an innovator in his day as it is believed that he was the first to foul off pitches deliberately.

Bob Rush may have had a losing record with the Chicago Cubs (110-140), but in his defense, he did not have a lot of strong teammates around him, and the Cubs were not particularly good at the time.  Still, we are talking about a two-time All-Star who finished in the top ten in bWAR for Pitchers four times and in Strikeouts four times.  He would record 1,076 Ks for Chicago and was one of the better players the team had in the 1950s.

Ned Williamson played the entire 1880's with the Chicago White Stockings, where his strength was his defensive skills.  Used at Third Base and Shortstop for most of his career, Williamson would twice lead the National League in Defensive bWAR and was in the top five in that statistic four other times.  Had there been a Gold Glove Award back then, Williamson would have likely won at least six (or should have) for his work at Third Base as even by traditional metrics, he was a six-time leader at his position in Assists and five-time leader in Double Plays Turned.

In retrospect, the Chicago Cubs stole Anthony Rizzo from the San Diego Padres in a trade in 2012 that saw little attention.  At that point in his career, Rizzo had only played 49 Games in the Majors, and while his future was thought to be bright, it wasn't expected that he would become the heart of the Cubs.