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6/6/2014 6:56 P.M. ET

Minor Leaguer Welker has Tommy John surgery

PITTSBURGH -- Pirates Minor League reliever Duke Welker underwent Tommy John surgery Thursday, ending his 2014 season.

Welker got a second opinion on his injured right elbow from Dr. James Andrews, who recommended and performed the surgery in Gulf Breeze, Fla. Welker, 28, was 1-1 with a 4.91 ERA, 15 strikeouts and 11 walks in nine appearances for Triple-A Indianapolis this season. He last pitched on May 3 before being sidelined with the elbow ailment.

Welker has a fastball that can touch the upper 90s and spent parts of the last three seasons in Triple-A. He also had a brief stint in the Majors last season, and in two appearances with the Pirates last June, Welker pitched 1 1/3 scoreless innings.

Worth noting

• Pirates reliever Vin Mazzaro cleared waivers and was assigned to Triple-A Indianapolis on Friday. Mazzaro was designated for assignment on May 26, when the Pirates promoted right-handed starter Brandon Cumpton. Mazzaro had a 3.48 ERA and 1.258 WHIP in five appearances this season.

• Starting Friday, 13 of the Pirates' next 16 games will be against National League Central opponents. The Pirates went into Friday 13-19 against divisional foes so far this year.

First number, last word

18: The number of consecutive games in which Pirates reliever Tony Watson has not allowed a run. Watson's 18 2/3-innings scoreless streak currently ranks as the fourth-longest in the National League.

"We encouraged him to go where you need to go, do what you need to do, but we'd love to have you back because we feel really positive and optimistic that there will be an opportunity for you here again." -- Manager Clint Hurdle on reliever Mazzaro clearing waivers and being sent to Triple-A Indianapolis

Stephen Pianovich is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.