The Astros shipped Johnson to Arizona on July 29 for two Minor Leaguers. Since joining the D-backs, Johnson has 18 RBIs in 15 games.
After hearing of the trade, Johnson, selected by Houston in the fourth round of the 2006 First-Year Player Draft, apologized to his Astros teammates for not being able to ride through the struggles of a rebuilding franchise.
"It was pretty emotional in the room when I got called in," Johnson said after the trade. "This is all I've known since 2006, when I was drafted. I called this place home. I moved here. It's definitely tough, but that's the way the game goes. I'm excited to move on to the Arizona Diamondbacks."
Two rookie left-handers who faced off on July 21 will take the mound again on Friday.
The D-backs' Wade Miley is a candidate for the National League Rookie of the Year Award, posting a 12-8 record and a 3.02 ERA. He's drawn the decision in each of his last 17 starts, going 9-8 over that span.
Against the Astros on July 21, Miley allowed one run over seven innings of work, striking out nine.
Astros left-hander Dallas Keuchel went six innings in his last start, allowing four runs (two unearned). Against the D-backs on July 21, Keuchel took the loss, allowing seven runs (six earned) in 3 1/3 innings.
Keuchel, who tries to pitch to contact and get ground balls, has cut down his walks recently. In July, he walked an average of four batters per start. In two starts in August, he's issued just one free pass.
Astros: Bogusevic looking to improve
Outfielder Brian Bogusevic, batting .216 with six homers and 23 RBIs during his first full season in the Majors, hasn't played up to his expectations.
"It's my first full season, so there's a lot of stuff I haven't seen before," Bogusevic said. "You have to take it as a learning experience and move on."
Last year, Bogusevic batted .287 with four homers and 15 RBIs in 164 at-bats. The Astros rewarded him with a starting spot in the outfield.
"Honestly, there's the experience of just facing that level of pitching day to day, but at the same time, there's things I learned about myself and what I need to do to keep my swing right and things I need to work on to be ready," he said.
The Astros will wear their throwback blue and gold star uniforms on Friday. Last weekend against the Brewers, the Astros wore the uniforms as part of "Flashback Friday."
When Houston picked up its first walk-off victory of the season on Friday, the players asked to wear them again on Saturday, when the club also won in walk-off style. The Astros wore them again on Sunday, but dropped the series finale.
D-backs: Saunders feeling better
D-backs left-hander Joe Saunders said he expects to be able to make his next start after being struck on his pitching hand by a comebacker Wednesday night.
Saunders reached his bare hand out to try and stop a shot back up the middle by Matt Holliday. The ball deflected off his thumb over to second baseman Aaron Hill, who threw Holliday out at first to end the inning.
Despite his hand being numb, Saunders told D-backs manager Kirk Gibson that he was OK to stay in the game.
"He's a hard head," Gibson said.
Saunders retired the first two batters in the sixth before allowing a pair of runs.
"It feels a lot better than last night," Saunders said. "Last night was a little numb when I tried to throw that next inning."
Houston is 12-48 on the road and 27-32 at home.