Middlebrooks signed a minor-league contract that includes an invitation to spring training with Philadelphia on Wednesday.
Middlebrooks appeared in 22 games with the Rangers, hitting just .211/.231/.368 with 14 strikeouts in 38 at-bats. The third baseman spent most of the season at the Triple-A level, and will likely begin 2018 with Lehigh Valley while serving as organizational depth for his new club.