Moustakas is hitting just .152 (19-for-125) in 40 games this season. On the plus side he has four homers, tied for the team high, and 17 RBIs but largely he's seemed lost at the plate.
"He looked lost and that's where it got to him," manager Ned Yost said. "The last day that he played, you could just tell that his confidence was suffering and he was just putting too much pressure on himself."
The move means that Danny Valencia will take over full-time at third base. Valencia was obtained from the Orioles last winter in a trade for outfielder David Lough just in case Moustakas faltered this season.
To fill Moustakas' roster space, the Royals recalled infielder-outfielder Jimmy Paredes from Omaha. Paredes, who played in four games for Kansas City earlier this year, has a .327 (35-for-107) average for the Storm Chasers with three homers and 17 RBIs in 26 games. He'll join the club for their series against the Angels at Anaheim starting on Friday night.
"It's the best thing for everybody right now," general manager Dayton Moore said. "You make decisions on what's best for the team and what's best for the player as well. We felt that keeping Moose up as long as we did gave us the best opportunity to win games at the time."
On Tuesday, Yost moved away from the platoon system he'd been using recently at third base, starting the right-handed-hitting Valencia at third base instead of the left-handed Moustakas against a right-handed starting pitcher.
Valencia responded with a 2-for-3 game against the White Sox's Andre Rienzo in a 7-6 Royals victory. He also started on Wednesday night against a left-hander and indications were that he'd get more opportunities in the near future. In 16 games, Valencia has a .308 (16-for-52) average with one home run and seven RBIs.
Yost felt that Moustakas' problems were becoming more mental than mechanical.
"You watch him take batting practice and he was absolutely dynamite but he got in the game and there was so much pressure to perform that he couldn't transition it. That's when it got to the point where I needed to give him a break," Yost said.
"Danny had a couple of good games and our thought process was that if Danny's going to play and do OK, we might as well get Moose in an environment where he can have some success and start feeling good about himself, get his confidence level back up and get him in a position where he can perform like we think he can."
Moustakas, who was given word of the move after Wednesday night's game, could not be reached for comment.
"But Moose, as you would expect, handled it very professionally. He's very appreciative of the organization. He loves the fans and he's got a great connection with the fans in Kansas City," Moore said.
"He's sad that he hasn't been able to produce the way he feels he can. But he understands that it's probably the best for him and the team right now. He's going to go to Omaha and play with that passion and that great heart that he has and get back here and help us, hopefully sooner than later."
All the signs were there in Spring Training for a Moustakas breakout season. He was hitting the ball hard, going opposite field on occasion and his .429 average was third-highest in the Major Leagues. His 18 RBIs in 24 games were the most in baseball and he had four homers and seven doubles.
"Spring Training is a no-stress situation and that just shows you what he's capable of doing when he's confident and swinging the bat good," Yost said.
Moustakas was coming off a productive winter ball session in Venezuela where his Cardenales de Lara manager was Pedro Grifol, the Royals' hitting coach. In 17 games, he hit .288 with three homers and six doubles in 17 games. Even better, as the result of intensive sessions with Grifol, the left-handed slugger was pounding the ball to left center and left.
The real season results, however, have been disappointing. There have been calls in the media for Moustakas' demotion but, until now, the Royals had resisted such a move.
Moustakas has trouble against left-handed pitchers (just 1-for-13 this year) so Yost took to using Valencia against lefties and he's 11-for-33, .333, against them. Opponents consistently employ a drastic shift to the right-field side for Moustakas, indicating his penchant for hitting to the opposite field has been minimal.
Oddly, the same pattern prevailed for Moustakas in 2013. Coming off a .242 average in his first full season, he ripped off a .394 mark in the Cactus League with five homers and 16 RBIs in 26 games. Then he batted .183 in the first two months of the season although he perked up enough in the second half (.301 in August) to finish at .233.
Telling figures, however, were his fall from 20 homers and 73 RBIs in 2012 to 12 homers and 42 RBIs in 2013.
Through it all, however, his fielding at third base has been exemplary. He was nominated for a Gold Glove in 2012.
Inevitably, comparisons have been made to demotions to Omaha dealt to designated hitter Billy Butler in 2008 and to left fielder (then third baseman) Alex Gordon in 2010. Both had productive stays and good stats with the Minor League club and returned the better for it.
Butler came back in 2008 to play 71 more games for Kansas City and hit .284 with 10 homers and 37 RBIs. In 2009, he broke loose for a .301 season with 21 homers and 93 RBIs and was voted Royals Player of the Year.
Gordon couldn't get going after hip surgery in 2009 and was shipped out early in 2010 to work on his hitting and, oh yes, to change positions from third base to left field. Back later in 2010, Gordon hit just .218 in 62 games but showed some power and proved he could play the outfield.
In 2011, Gordon hit .303 with 23 homers, 87 RBIs, won a Gold Glove and was Royals Player of the Year.
Now it's Moustakas going to Omaha.
"Moose will certainly do his part," Moore said. "He'll work hard and play hard the way he always does and good things will happen for him."