The Reds traded Wiemer and Jonathan India to the Royals on Friday in exchange for Brady Singer.
Wiemer went just 4-for-26 with nine strikeouts in 21 big-league games played between Milwaukee and Cincinnati last season. His performance in the minors wasn't great either, as he slashed .189/.277/.226 in 119 plate appearances with the Reds' Triple-A affiliate after being traded at the deadline. Once regarded as a top prospect in the Brewers' farm system, the 25-year-old Wiemer will look to turn things around with the Royals, though he will likely report to Triple-A Omaha.