6. The Jose Quintana/ Dylan Cease trade
Another crosstown deal from the 2017 trade deadline, this trade will undoubtedly go down as one of the worst for the Chicago Cubs. Finding themselves in the middle of a World Series hangover and in need of another starting pitcher, the Chicago Cubs front office took a big swing by trading the top pitching prospect Dylan Cease and power-hitting corner outfielder Eloy Jiminez to the White Sox for left-handed starter Jose Quintana. At the time, this deal was justified since Jose Quintana was a durable starter coming off four straight seasons where he made 32 starts each with an ERA in the mid-to-low 3 range.
But once Quintana got to Wrigley Field, he looked like a shell of his former self and he failed to have an ERA below 4 during his tenure. Although he kept his durability for the most part, the end of his run in Chicago is mired in embarrassment since he missed most of the shortened 2020 seasons after slicing his pitching hand open while doing dishes at home, prompting season-ending nerve repair surgery.
Dylan Cease on the other hand (pun intended) has emerged as one of the best strikeout pitchers in the league and he finished second in CY Young voting in 2022. Although he doesn't look as sharp as he did in 2022, Cease continues to strike out more than a batter per inning in 2023 while Eloy Jiminez is perennially hurt.