July 31, 2008: Ken Griffey Jr., Reds to White Sox
No longer “The Kid,” the 38-year-old Griffey was at the time of this deal in the final year of the nine-year, $116.5 million extension he had signed to facilitate his 2000 trade from the Mariners to the Reds. Though he had been an All-Star for the 13th time in his career the season before, he had slipped into mediocrity by that point, and 2008 didn’t reverse the trend. Traded in exchange for righty reliever Nick Masset and infielder Danny Richar, Griffey hit just .260/.347/.405 with three homers in 41 games for the White Sox, though his bat perked up in the final week as the team regained its recently-squandered AL Central lead, ultimately beating the Twins in a Game 163 tiebreaker.
After the season, Griffey returned to the Mariners for what would be a less-than-fruitful reunion. Even so, an impressive resumé highlighted by those All-Star appearances, 10 Gold Gloves and 630 home runs (sixth all-time) led to his receiving a record 99.3% of the writers’ vote when he became eligible in 2016.