The Royals designated Falter for assignment Wednesday.
Kansas City will drop Falter from its 40-man roster after the veteran lefty was roughed up for nine earned runs in 4.1 innings over his previous two starts, during which he served as an opener in bullpen games. The 29-year-old didn't fare much better in his three relief appearances with Kansas City before that, yielding six earned runs over 5.1 innings. The Royals will replace Falter with a fresh relief arm in right-hander Mason Black, who was recalled from Triple-A Omaha ahead of Wednesday's series finale versus the Yankees.