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8/21/2014 7:06 P.M. ET

Hoover, Contreras optioned to Triple-A

CINCINNATI -- It's been a struggle of a 2014 season for Reds reliever J.J. Hoover, and it reached a low point on the previous road trip when he was on the mound for two walk-off losses. The Reds made roster moves Thursday and Hoover was optioned to Triple-A Louisville.

Hoover is 1-10 with a 5.27 ERA in 46 games, which tied the Reds' record among relievers for most losses in a season. His 10-game losing streak is a record for Cincinnati relievers. He 10th loss came when he hit Jon Jay with the bases loaded in the ninth inning for a 5-4 loss to the Cardinals on Tuesday.

"J.J. was the choice simply because it's been such a battle to just really be consistent and be the same guy we've come to know from 2012 and 2013," Reds manager Bryan Price said. "I think a few outings down in Triple-A just to get his feet back on the ground hopefully will help him when he comes back. He'll certainly be back with us in September and hopefully throwing the ball as good as ever."

Also optioned to Louisville was rookie Carlos Contreras, who had a 6.11 ERA in 13 appearances. Contreras exited Wednesday's game at St. Louis in the eighth inning with right shoulder stiffness but it proved not to be a serious issue.

To fill the 25-man roster, the Reds recalled lefty pitcher David Holmberg from Louisville to start vs. the Braves on Thursday. Right-handed reliever Pedro Villarreal, who had one-game stints in the big leagues for the Reds in 2012 and 2013, was also called up.

Villarreal had a 3.20 ERA in 42 games this season for Louisville. In the Reds' 8-0 loss to the Braves, he replaced David Holmberg in the third and allowed two runs and three hits over 2 1/3 innings.

Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.