Dickerson, who is batting .277 overall, is hitting .452 (14-for-31) over his past 12 games and has hits in 10 of them. He struck out as a pinch-hitter in the ninth inning on Tuesday.
Hanigan is batting .321 for the season.
"You can't play everybody," Reds manager Dusty Baker said. "I have a plan on how to keep them sharp and productive for themselves and us at the same time. We knew that could potentially happen when we started. You don't have a good team unless you have too many good bodies."
With right-handed pitcher Dan Haren on the mound for Arizona, lefty hitting Laynce Nix started in left field instead of Gomes. Willy Taveras, who came in batting .237, led off and played center field.
Gomes, who struck out as a pinch-hitter in the seventh inning of a 6-2 loss to the D-backs, is Baker's left fielder vs. left-handed pitching, which he bats .417 against. Arizona is expected to start southpaw Doug Davis on Thursday.
"He's been deadly against lefties," Baker said. "Dickerson is making big progress against lefties. That's why I'm not afraid to throw him in there."
Hanigan saw his playing time dwindle once Joey Votto returned from the disabled list. Regular catcher Ramon Hernandez (.246 average entering Wednesday) played first base while Votto was out.
"Ramon has been one of our best, clutch RBI guys," Baker said. "Even though his average isn't indicative, but his runners in scoring position [.321 average] and his RBI total  is."
Hernandez hit a one-out RBI double in the seventh inning on Tuesday.
CIN: RHP Johnny Cueto (7-4, 2.86 ERA)
Cueto was roughed up for his second straight start in Toronto on Thursday. The right-hander pitched six innings, allowing five earned runs and five hits, while striking out four and walking three in a 7-5 win over the Blue Jays. Cueto will try to return to form against the D-backs. He is 1-0 with a 1.50 ERA in two starts against Arizona in his career.
ARI: RHP Jon Garland (4-7, 5.04 ERA)
Garland has not won since May 19, a span of seven starts. In fairness, there were a few games during that stretch when he pitched well enough to win. His last outing against the Rangers was not one of them. The right-hander allowed six runs (four earned) on eight hits over 6 1/3 innings in what turned out to be a 9-8, 12-inning loss. His start prior to that, however, was a dandy. He tossed seven shutout innings in that one only to walk away with a no-decision. There has been a significant home/road split for him this year. In eight games at Chase Field, he is 2-4 with a 7.51 ERA while in seven road starts he is 2-3 with a 2.60 ERA.
The Reds' bullpen entered Tuesday's game ranked second in the National League with a 3.34 ERA but has not been overworked to this point. Cincinnati relievers were ranked 11th in innings pitched.
"That's how you want it," Baker said. "Everybody can be strong down the stretch. I always want it but it doesn't always work out like that. ... When you have an overworked bullpen, then you're going on who is most rested vs. who should be facing whom. That's a bad situation and a bad feeling right there."
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Official game notes
Thursday: Reds (Aaron Harang, 5-8, 3.95) vs. Diamondbacks (Doug Davis, 3-8, 3.28), 12:35 p.m. ET
Friday: Reds (Homer Bailey, 1-0, 8.68) vs. Cardinals (TBD), 7:10 p.m. ET
Saturday: Reds (Micah Owings, 5-8, 4.63) vs. Cardinals (TBD), 1:10 p.m. ET