Robertson, ranked No. 87 on MLBPipline.com's Top 100 Prospects, hit his home run in the third off left-hander Tyler Anderson, the Rockies' No. 12 prospect and the Texas League Pitcher of the Year. At the time, the solo blast cut the RockHounds' deficit to two runs.
Robertson finished the game 1-for-3 and was hit by a pitch. First baseman Max Muncy, the A's No. 9 prospect, also went 1-for-3 with a home run and a walk.
After Stockton was eliminated from the California League playoffs last week, the A's promoted Robertson to Midland. He has played four games for the RockHounds, all at second base. He is 2-for-12 at the plate with two runs and two RBIs.
During the regular season with Stockton, Robertson hit .310/.402/.471 with 15 home runs in 132 games. The 20-year-old primarily played shortstop and ranked second in the California League in runs (110), fourth in on-base percentage and sixth in batting average.
Now, Robertson is trying to help the RockHounds to their first Texas League championship since 2009. After a travel day, the best-of-five series shifts to Midland for Game 3 on Friday. First pitch is scheduled for 9 p.m. PT.
Teddy Cahill is a reporter for MLB.com. Follow him on Twitter at @tedcahill. This story was not subject to the approval of Major League Baseball or its clubs.