CHICAGO -- The Pittsburgh Pirates say top pitching prospect Jameson Taillon has undergone Tommy John surgery on his right elbow.
The procedure was performed Wednesday in New York by Dr. David Altchek. Taillon is expected to miss 12 to 18 months.
Taillon began feeling pain in his elbow with two weeks remaining in spring training after being assigned by the Pirates to their minor league camp. Doctors prescribed two weeks of rest, but Taillon again felt pain when he tried to throw again.
The Pirates also said right-handed reliever Vin Mazzaro accepted his outright assignment on Wednesday. He is expected to join Triple-A Indianapolis in the coming days.