Bronson Arroyo (1-0) gave up three runs in six innings, including Josh Hamilton's two-run single that was his first hit for the Angels. Albert Pujols drove in a pair of runs with a sacrifice fly and a groundout.
Nobody enjoyed Choo's homer more than Arroyo. Choo has four career homers off Arroyo, his highest total off any pitcher. The Reds got him from Cleveland in the offseason.
"Every time he goes deep for me, it's like a holiday," Arroyo said.
Left-hander Aroldis Chapman pitched the ninth, converting his first save opportunity. Mike Trout led off with a single and was sacrificed to second, but Pujols flied out and Hamilton struck out.
The teams combined for seven homers and 63 strikeouts during the series. The Reds fanned 36 overall, a club record for the first three games of a season. The 36 strikeouts were an Angels record for a three-game series.
Their biggest hitters also have had a tough time getting started.
Pujols and Hamilton were a combined 0 for 17 with six strikeouts before they finally put something together in the third inning. Pujols doubled for his first hit, and Hamilton followed with a two-run single; Pujols slid into home safely while catcher Ryan Hanigan missed his leg while attempting the tag.
Pujols also had a sacrifice fly and a run-scoring groundout, limping on his left foot after he'd run. Pujols is playing through pain from plantar fasciitis.
Choo got the Reds started with his sixth career leadoff homer. Frazier led off the second inning with a homer just inside the left field foul pole, and Heisey connected in the fifth.
The game featured the first replay of the season at Great American Ball Park. Frazier's fly ball went off the yellow padding atop the wall in the fourth, and he continued to third when Trout bobbled the carom for an error. The umpires checked to make sure the ball didn't clear the wall. Frazier scored on Hanigan's sacrifice fly - Cincinnati's only run that didn't come off a homer.
Baker got through the series without using left-handed setup man Sean Marshall, who's had some tiredness in the front of his pitching shoulder the last couple of weeks. Marshall said Thursday he felt much better and should be available for the opener of a series against Washington today.