TRENTON — After putting together a nearly unblemished first half, David Phelps has been promoted to Triple-A Scranton/Wilkes-Barre. The move, although it hasn’t been officially announced by the team, was confirmed by multiple sources before the Thunder’s game with the Harrisburg Senators.

The right-hander, who was not in the ballpark yesterday, was 6-0 with a league-best 2.04 ERA and 84 strikeouts over 88 1/3 innings before the move up.

“Let’s face it, David did a heck of a job. He’s a pretty polished pitcher at this level.” manager Tony Franklin said before the game. “He proved that, and proved it with consistent outings. For half the season, you could always depend on him. That’s what we’re losing.”

With the move, the Thunder are left with one pitcher, D.J. Mitchell, remaining from the rotation to start the season. Jeremy Bleich is out for the season after surgery to repair a torn left labrum, Christian Garcia underwent his second Tommy John surgery and was released, and Ryan Pope has been shifted to the bullpen.

Phelps will start tonight for Scranton, who are in the middle of a series in Pawtucket. He takes the place of Dustin Moseley, who is being called up to avoid him triggering an out clause in his contract.

To open a spot on the major league roster, a reliever, believed to be either Chad Gaudin or Chan Ho Park, is likely to be designated for assignment.

Phelps’ departure also opens a spot on the Eastern League Eastern Division All-Star team. The Thunder have asked the league to fill that slot with Mitchell, who is 6-3 with a 4.70 ERA through 14 starts.

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After an awful outing during their last home game, the Thunder have placed closer Grant Duff on the 7-Day Disabled List with right elbow inflammation. Although the team does not like to place designations on pitchers’ roles, it is likely Tim Norton will slide in to the back-end role.

Duff stressed that he believes the injury is minor and should not cost him serious time.

Taking his roster spot is right-hander J.B. Cox, the Yankees’ second-round choice from 2005. He racked up an 8.59 ERA in five games with High-A Tampa before getting the promotion.

Cox is working his way back after taking a nearly year-long leave absence to ponder his future in baseball. His last game action in 2009 was June 25 with Trenton, the second of back-to-back poor outings in against the Akron Aeros.

During those appearances, Cox allowed four earned runs on four hits and four walks in a combined inning of work.

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Because Franklin is heading to the XM Futures Game, which will be held at Angel Stadium on July 11, an interim manager will be needed for the team’s last two first-half games, to be played at Prince George’s Stadium against the Baysox on July 11 and 12.

Jody Reed, who performed the same task last year for Franklin, will fill his shoes again.