Mathias was optioned to Triple-A Indianapolis on Monday.
As the Pirates thin their major-league roster out ahead of Opening Day, Mathias will make his way to Indianapolis. The 28-year-old produced a .222 average with a double, two RBI, a run scored and two stolen bases over 18 at-bats in eight games this spring. After signing a contract with the Pirates this offseason, Mathias will have to prove himself at the Triple-A level before he'll get a shot at the big leagues.