Arroyo, with no homers in his first six major league seasons, hit his second off Rusch in the past week, one of six long balls by the Reds as they routed the Cubs 9-2 on a windy Tuesday at Wrigley Field.
"I got lucky again. Just keep hacking," Arroyo said after throwing seven shutout innings and hitting a ball over the left-field bleachers that landed on Waveland Avenue.
"I really just couldn't believe where the pitch was because it was almost identical to last time. ... I was a little surprised," he added. "I knew the wind was going out, I got it good, like I did last time. I figured that it wasn't going to land anywhere in the park."
Adam Dunn hit a pair of solo shots and Ken Griffey Jr. and Arroyo had one each off Rusch in the first four innings. Edwin Encarnacion hit his first career grand slam and Austin Kearns followed with another homer, both off Will Ohman in the sixth.
"He's got more homers than Wily Mo already," Dunn said of Arroyo, who was traded from the Red Sox on March 20 for Wily Mo Pena.
"He's got a good swing. That's impressive. He's shown me two tools so far."
Arroyo, who hit his first homer since high school off Rusch on April 5 at Great American Ball Park, connected for the Reds' third of the game leading off the third. Arroyo's homer last week was his first hit since 2001.
"I don't have anything for you," Rusch said, unable to explain how he could give up two homers to the same previously light-hitting pitcher in less than a week. "He took two pitches and hit them good. Other than that there is nothing I can say."
Arroyo (2-0) also pitched well in beating Chicago for the second time in two starts, an outing made easier by all the run support. He shut down the Cubs and ended their three-game winning streak, allowing six hits.
"Luckily for us we just got more balls in the air than they did," Arroyo said. "These guys can do enough damage on their own but I guess if I can help out the cause, I'll keep doing it. If the wind is blowing out, we have a team that can put up some runs. That gives confidence to the starting pitching."
With the wind blowing out at 17 mph, Griffey connected on a long solo shot off Rusch in the first, his second of the season and 538th of his career. Dunn hit an even longer one in the second, a drive to center. He connected again in the fourth.
"It's the first time I've seen four solo homers in the first four innings," Cubs manager Dusty Baker said.
Rusch (0-2) also yielded two homers last week to the Reds in an 8-6 loss. He gave up five hits, four of them homers, and four runs in five innings.
"If the elements play that much into effect as today, look at the way Arroyo threw the ball. He threw seven shutout innings on the same mound and same field as I did," Rusch said. "I didn't make good pitches."
Ohman didn't either. He couldn't get a batter out in the sixth.
Leading 4-0, the Reds loaded the bases when Cubs third baseman Aramis Ramirez and shortstop Ronny Cedeno had a mix up and let Griffey's wind-blown pop fall for a single in short left, Rich Aurilia singled and Dunn walked. Encarnacion followed with his grand slam and Kearns hit the Reds' fifth solo shot of the day as the boos poured down.
- Cubs RHP Mark Prior, working his way back from a strained shoulder muscle that landed him on the DL, threw about 30 pitches from the bullpen mound before the game. Pitching coach Larry Rothschild said Prior has progressed to a point where he doesn't feel any pain. He will throw again Friday in Arizona.
- Before his homer last week in Cincinnati, Arroyo was 4-for-55 career with 33 strikeouts. He finished 1-for-3 Tuesday.
- It was the most homers allowed by a Cubs pitching staff since giving up seven to the Astros on Sept. 9, 2000, in a 14-4 loss at Wrigley.
- Chicago RF Jacque Jones left in the sixth with a strained right hamstring and had an MRI. Trainer Mark O'Neal said he didn't expect the injury to be serious. Ramirez hurt a muscle in his buttocks on a swing late in the game.
- Dunn has 16 career two-homer games.