"Today we dug ourselves a little bit of a hole early and they never let up, kept their foot on the gas pedal," Walker said. "We have to continue to play good baseball here and things are going to go our way."
Jay Bruce hit a three-run double and Todd Frazier followed with a homer that capped a five-run burst in the first inning. Bronson Arroyo (14-11) made it stand up, lasting five innings to win for the first time in nearly a month.
Cincinnati rookie outfielder Billy Hamilton kept creating havoc. Hamilton went 3 for 6 with double and two more stolen bases. A record-setting basestealer in the minors, he is 12 for 12 on swipe tries since his late-season promotion from Triple-A. Chris Heisey, batting behind Hamilton, went 3 for 5 with a double and two RBI as the Reds put the pressure on Pittsburgh from the outset.
"Those guys set up some big innings," Cincinnati manager Dusty Baker said. "You need guys in your lineup to drive in runs but it's just as important to have guys to get on base so they can be driven in."
Cincinnati loaded the bases with one out against Locke in the first when Bruce doubled to the gap in left-center field to clear the bases. Frazier followed with his 18th homer, a two-run shot to the deepest part of PNC Park.
Cincinnati pushed its advantage to 7-0 in the second on an RBI double by Heisey and a sacrifice fly from Brandon Phillips off reliever Jeanmar Gomez.
Staked to such a huge cushion, Arroyo worked quickly if not exactly effectively. Walker hit his third homer in four games leading off the third and pinch-hitter Travis Snider did the same in the fifth.
Pittsburgh's best chance to make it close came later in that inning when Walker's double put runners in scoring position with no outs. Arroyo surrendered only a sacrifice fly by Justin Morneau that made it 7-3. The veteran right-hander gave up three runs on five hits in five innings, walking two and striking out three.