Nationals right-hander Collin Balester pitched five innings and gave up five of the seven runs. Four of them came on a pair of two-run homers by Gomes. The other was on a solo homer by Ryan Hanigan.
Balester has given up nine home runs in 24 innings. One reason he has given up so many homers is because his a four-seam fastball has been too straight.
"If you are going to do that, you really have to hit your spots -- in and out," Nationals interim manager Jim Riggleman said. "You can't leave it over the middle of the plate. If you do, they are going to hurt you."
Ironically, Balester said it was the best his arm felt all season, but the box score tells a different story.
"I felt like I pitched the best that [I could]," Balester said. "But those three pitches [I left in the zone], I need to work on [getting those pitches down] and keep my tempo [going]."
Gomes hit his third home run of the game on a 2-2 pitch by reliever Jason Bergmann, driving the ball over the center-field wall in the sixth.
"That's the best performance I've seen in a long time," Reds manager Dusty Baker said about Gomes. "We needed runs and we needed a victory."
Bergmann said he and catcher Josh Bard agreed to throw a high fastball to Gomes. The problem was, the ball wasn't high enough.
"I threw him one or two quality pitches out of seven or eight," Bergmann said. "The only pitch I hadn't thrown was a fastball up. Bard and I agreed that was the only pitch to throw. If it was up a little more, he was going to pop up. He was obviously seeing the ball well today."
Arroyo proved to be too much for the Nationals, completing his third complete game of the season and giving up just two hits. Adam Dunn, making his first appearance at Great American Ball Park since the Reds traded him to the D-backs on Aug. 11 of last year, and Ryan Zimmerman collected those hits in the second and seventh innings, respectively.
The reason Arroyo was so effective was because he was throwing his fastball for strikes.
"He has great offspeed stuff. Everybody knows that," Dunn said. "But when he is throwing that fastball for strikes and put it anywhere he wants, he is tough.
Said Riggleman, "He's a good pitcher. He's a pro and he changed speeds. He seemed like he threw pitches from about three different arm angles. He threw strikes with his fastball. He had a couple of breaking balls where he was able to freeze hitters. It seem like we were hitting the ball at the end of the bat all day. That's a [tribute] to what he was able to do out there. We just couldn't square him up."
The Nationals have lost three consecutive games. Unlike the previous two games, Washington looked flat, and Riggleman told his players that in a closed-door meeting after the game.
"You look flat when you get two hits and you don't have many baserunners," Riggleman said. "You have to create some energy. You have to be hustling down the line. You have to be running balls out. You hit fly balls, you have to round the bag hard.
"You are trying to send a message to that other dugout: You are beating us, but we'll be coming at you. I think our guys have done a good job of it, but, tonight, we didn't get after it the way we [have on other nights]."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.