Moustakas, 25, has been considered a key piece of the Royals' long-term future since the organization selected him behind Tampa Bay's David Price with the No. 2 overall pick in the 2007 first-year player draft. He hit 20 homers and drove in 73 runs in his first full season with Kansas City in 2012, but he's continued to regress over the past two years.
In 40 games this season, Moustakas was hitting .152 (19-for-125) with a .543 OPS. He was batting .109 (6-for-55) at Kauffman Stadium.
When speculation began to surface recently about a possible demotion for Moustakas, Royals general manager Dayton Moore and manager Ned Yost both praised his defense and expressed faith in him as Kansas City's long-term answer at third base.
"He's a guy that's going to help us win a championship," Yost told reporters.
But the Royals were unable to wait for Moustakas to snap out of his funk given the team's overall offensive issues. With veterans Billy Butler and Alex Gordon also off to slow starts, Kansas City is last in the American League with a .668 team OPS and is tied with the Texas Rangers for 12th in the American League with 181 runs scored. The Royals have hit a major-league-low 20 home runs in their first 46 games.
Paredes is expected to share time at third base with Danny Valencia in Kansas City while Moustakas tries to find his stroke in Omaha.