The New York Mets announced that staff ace Johan Santana was placed on the 15-day disabled list and is not expected to take the mound for the remainder of the season thanks to back issues.

In a statement released on Wednesday, the Mets said that an MRI taken on Tuesday revealed lower back inflammation, but surgery was not an option in favor of rest and medication.

The 33-year-old lefty is going through his most disappointing season in a 12-year pro career, with a 6-9 record and 4.85 earned run average in 21 starts.

He was out of action from July 20-August 11 thanks to a right ankle injury, and has not won since June 30 at Los Angeles -- dropping all five of his starts since then.

Santana already was forced to the sidelines early in 2009 due to surgery to remove bone chips in his pitching elbow, then was shut down in 2010 thanks to a tear in the anterior capsule in his left shoulder. That issue, eventually also corrected by surgery, cost him the entire 2011 season.