Singleton was optioned to Triple-A Fresno on Wednesday, Brian McTaggart of MLB.com reports. Singleton's spring average was over .300 at one point, but he struggled mightily over recent Grapefruit League play, going 1-for-21 with nine strikeouts before his eventual demotion. The 23-year-old even admitted the move was necessary after hitting .200/.273/.320 with six doubles, four RBI and 18:5 K:BB over 50 Grapefruit League at-bats. Chris Carter figures to step in as the Astros' primary first baseman to open 2015.