Van Slyke hit a solo homer and a three-run shot off Cingrani (2-7), who could lose his spot in the rotation when Mat Latos returns from the disabled list later this week. Cingrani gave up a career-high six runs in 4 2-3 innings of his fifth straight loss.
The Dodgers like Van Slyke for his versatility. He has started four games in center, 11 in left and three at first base. The problem is that there's no room for him to have a regular spot.
''I know what I'm here for, so I don't mind it,'' Van Slyke said. ''I'm not going to complain.''
Nor will the Dodgers.
''He's been good for us all year,'' manager Don Mattingly said.
''This guy's just kind of slowly showing his value over time. He's a guy that sneaks up on you. Plays all three outfield spots really well."
''I think he's a guy that you could expand his role. Obviously that's not here right now.''
Dan Haren (6-4) gave up five hits in 5 1-3 innings, including Ryan Ludwick's solo homer, for his first win since May 12. Brandon League escaped a bases-loaded, no-outs threat in the eighth by getting Ludwick to hit a comebacker that led to a home-to-first double play.
Haren opened the season 4-0 and has been trying to get back into form the past month.
''I started the year throwing the ball very well,'' Haren said. ''I've just really been mediocre here for a while. Today the bullpen picked me up.''
The Dodgers have gone 3-1 at the start of their seven-game trip to Colorado and Cincinnati despite hip injuries to right fielder Yasiel Puig and second baseman Dee Gordon. Puig was back in the lineup on Monday and had a single and a walk. Gordon pinch hit in the ninth and beat out an infield single.
The Dodgers and Reds have played a lot of close games the last two seasons. Six of their last seven had been decided by one run, with Cincinnati holding a 4-3 advantage in those games.
Van Slyke made this a comfortable win for the Dodgers, getting a career-high three hits. In addition to the homers, he singled and walked twice, reaching base in all five plate appearances.
Van Slyke came into the game with four homers and seven RBIs. He led off the second inning with a homer and ended Cingrani's outing with a three-run shot in the fifth that made it 6-2. It was his second career two-homer game.
Cingrani has struggled since he returned from an inflamed shoulder that landed him on the disabled list. He's 0-5 in those five starts with a 6.26 ERA and nine homers allowed. The left-hander gave up seven hits - matching his career high - and three walks on Monday.
The Reds fell to 3-4 on their 10-game homestand, leaving them fourth in the NL Central.
Haren had one rough inning, helping the Reds tie it 1-all in the second. Brayan Pena snapped a career-worst 0-for-17 slump with a single, and Zack Cozart singled. The runners advanced on a wild pitch, and Pena scored when Haren bounced a pitch to Cingrani with two outs.
This article originally appeared on FOXsports.com