KANSAS CITY, Mo. -- The Kansas City Royals traded outfielder Nick Heath, who had been designated for assignment earlier in the week, to the Arizona Diamondbacks for minor league pitcher Eduardo Herrera on Saturday.

The 27-year-old Heath, a speedster with a spotty bat, has been on the fringe of making the Royals' major league club the past several years. He finally made his debut last year, appearing in 15 games in the shortened season for Kansas City.

With a glut of outfielders, though, the Royals decided to trade Heath for some additional bullpen depth.

The 21-year-old Herrera signed with Arizona as an international free agent in 2016. He began his career as a catcher and infielder but converted to pitching two years ago with promising results. He has yet to move beyond Class A.