When the Royals traded for third baseman Danny Valencia last month, there was speculation that the club might try a platoon system at third base with Mike Moustakas. Valencia has raked left-handers during his career to the tune of a .329/.367/.513 slash line in 428 plate appearances. Moustakas’ career slash line against lefties is .222/.275/.332, so talk of a platoon was no surprise. However, it’s not going to happen. “Mike Moustakas is our everyday third baseman,” Royals general manager Dayton Moore said. “It just gives us more depth, and our job as a baseball operations staff is that Ned (Yost) and the coaching staff have as much depth as possible and are in a position to match up as they see fit on any given night.” Moustakas, who was drafted by the Royals in 2007, was in Baseball America’s top 100 prospects list each year from 2008-11, capped by being the No. 9 overall prospect before the 2011 season. After clubbing 20 home runs in 2012, Moustakas struggled through a rough 2013 campaign. After the season, he went to Venezuela to play in the winter leagues. In 17 games for Cardenales de Lara, Moose batted .288, with three home runs, six doubles and 17 RBIs. He had an on-base percentage of .360 and a slugging percentage of .515. Moustakas worked with Royals hitting coach Pedro Grifol, who was Moose’s manager in Venezuela. Grifol gave Moore a positive report.