2. The Ryan Theriot and Ted Lilly deal
The Chicago Cubs began their steep decline in the 2010 season, where they traded two of the best players of that era to the Dodgers at the trade deadline. Left-handed starting pitcher Ted Lilly spent 3 and a half seasons in Chicago, where he threw 700 innings with a 3.70 ERA. Lilly was a rock for the Cubs rotation in those years and his departure was an unfortunate sight. Similarly, infielder Ryan Theriot was a fan favorite among Cubs fans for several years. With his speed and ability to hit for contact, Theriot was a serviceable middle infielder and leadoff man for a time.
Despite the value of these players, the return for the Cubs turned out to be horrendous. The main player sent to the Cubs was infielder Blake DeWitt, who played just over a season's worth of games for Chicago over a three-year period. After being designated for assignment in the 2012 offseason, DeWitt signed a minor league contract with Atlanta and was out of the league by the end of 2013.
The Cubs also received pitchers Brett Wallach and Kyle Smit in the deal, neither of whom ever made it to the Major League level.