The Rockies designated right-hander Alan Johnson for assignment to create space on the 40-man roster, the team announced (on Twitter). In corresponding moves, Colorado called up Alfredo Amezaga and optioned Clayton Mortensen to Triple-A.
Johnson started one game for the Rockies this year, surrendering 6 hits, 3 walks and 4 earned runs in 4 innings of work on April 17th, when he made his MLB debut. The 27-year-old has since been demoted to Triple-A, where he has a 0.84 ERA with 5.9 K/9 and 1.7 BB/9 in 10 2/3 innings of work. Baseball America did not list Johnson among its top 30 Rockies prospects before the season.