ST. LOUIS -- Lefty reliever Zach Duke, who made 28 appearances for the Cardinals after being acquired on July 31, will not make another in 2017.
General manager John Mozeliak confirmed that Duke recently underwent surgery to repair his ulnar collateral ligament as well as a forearm flexor muscle in his left arm. Recovery from the surgery is expected to take between 12 and 18 months.
"It's definitely disappointing. He did a really good job for us, and I was looking at him as being a key member of that bullpen," Mozeliak said. "We'll look at it and figure out how to best solve this moving forward."
This news has already thrown a wrinkle in the Cardinals' developing offseason plans, as it will force the organization, Mozeliak acknowledged, to look more seriously at the reliever market.
As the Cardinals sought to fortify their bullpen at the non-waiver Trade Deadline, they pursued Duke partially because he was also under contract next season. Now, the club is on the hook for the $5.5 million he is due in 2017. That is the final year of Duke's contract.

The first indication that Duke was dealing with arm troubles came during the final week of the regular season. After pitching six times in a seven-day span, Duke was deemed unavailable by manager Mike Matheny for the team's final series. At the time, Matheny cited arm discomfort and usage concerns as the reasons for being cautious.
Once the season ended, the Cardinals ran Duke through a series of medical exams. It was then that they discovered the severity of his injuries.
Between the Cardinals and White Sox, Duke made 81 appearances in 2016. Only San Diego's Brad Hand tallied more. Duke finished with a 2.36 ERA and held opponents to a .217 batting average. He was even stingier after coming to the National League. With the Cardinals, Duke allowed five runs in 28 appearances while filling a setup role.
While the Cardinals begin planning for a 2017 team sans Duke, they also wait to learn whether Tyler Lyons and/or Seth Maness will be viable bullpen options by Opening Day.
Maness is expected to need six-to-nine months to recover from elbow surgery, which he underwent in August. Mozeliak said that by early December the club should "have a really good sense" of how likely it is that Maness will be healthy by the start of Spring Training.
Lyons' season ended when he required right knee surgery in August. The Cardinals expect to have a better feel for his recovery timetable next month.