Between April 23 when he was acquired and May 7 when he was optioned, the outfielder had 11 at-bats and two hits for a .182 average in six games. He also scored a run and had an RBI.
Robertson said he's thrilled to be back, but would be ready to embrace a role that could involve going back and forth between the majors and Triple-A.
"Every day is a new day. If you've got to go down there, you've got to work on things, you've got to play hard, you've got to take the same mentality," Robertson said. "Nothing changes, it's still baseball. It's still the same game up here as it is down there the last time I checked."
With the Express in Round Rock, Robertson had one home run, one triple and three RBIs in seven games. He batted .222.
"It's good to just kind of get my feet wet," he said. "It's just different ... I'm used to playing 135-plus games a year, and now I've only played 11 games the entire year."
Grace Raynor is an associate reporter for MLB.com
This story was not subject to the approval of Major League Baseball or its clubs.