Antonio Bastardo was the only dependable lefty reliever the Phils had in 2011. Philadelphia has since added veteran Dontrelle Willis as a free agent. Horst, who will be a Minor League invitee to Spring Training, and Joe Savery are also expected to compete for spots.
Horst made his Major League debut for the Reds last season and appeared in 12 games for Cincinnati with a 2.93 ERA. In 36 games at Triple-A Louisville, Horst had a 2.81 ERA and allowed 41 hits in 51 1/3 innings with 42 strikeouts and 14 walks. He held opponents to a .219 batting average.
Horst made six appearances of three innings or more for Louisville with an 0.83 ERA in those games.
Valdez had been a valuable and versatile backup for the Phillies over the past two seasons. As injuries forced Jimmy Rollins, Chase Utley and Placido Polanco from the lineup at various times over the past two years, Valdez started a total of 70 games at shortstop, 68 at second base and 28 at third.
His most memorable Phils moment, however, may have occurred in the early morning hours of May 26, 2011, when he came in to pitch the top of the 19th inning against the Reds at Citizens Bank Park. Valdez retired the side without giving up a run and earned the win when Philadelphia scored in the bottom of the inning.
Valdez, 33, recently signed a one-year, $930,000 contract to avoid arbitration. In the past two years, Valdez batted .254 with a .300 on-base percentage in 210 games. He previously played for the White Sox, Mariners, Padres, Dodgers and Mets.
The most likely candidate to fill his role with the Phillies in the upcoming season is Michael Martinez, the former Rule 5 Draft choice, who not only played third, second and short last season, but also left and center field.
The Phils now have 38 players on their 40-man roster.
Paul Hagen is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.