PITTSBURGH -- The Pittsburgh Pirates were once again able to wait out the Colorado Rockies' starting pitcher and attack the bullpen.
Andrew McCutchen knocked in the go-ahead run with a single in the seventh and Neil Walker added insurance two batters later with his 14th home run to propel the Pirates to a 5-3 victory and a three-game sweep.
"We were just able to put some good swings on guys out of their bullpen," Pirates manager Clint Hurdle said. "Our starters competed really well."
Walker finished 3-for-4 with two runs scored while leading his team to its second series sweep of the year and the third comeback victory in as many games.
Colorado's loss drops the Rockies to a season-worst 18 games below .500, with losses in three straight games in which the bullpen allowed Pittsburgh to take the lead.
"You've got to be a able to put games away and it's frustrating," manager Walt Weiss said.
The Pirates came back to win for the 25th time this season, accounting for nearly half of their 52 wins.
Pittsburgh starter Jeff Locke began his start in an uncharacteristic fashion when he walked the first batter he faced, left fielder Brandon Barnes. Shortstop Josh Rutledge then hit a two-run homer for an early 2-0 lead.
In the second, catcher Michael McKenry led off with a home run to left on a 1-1 changeup left over the middle of the plate.
In his first two innings of the second half, Locke allowed nearly as many home runs (two) as he did in eight first-half starts.
"The runs come in early and kind of put the team and you in a bad spot right away," Locke said.
Despite falling into a "bad spot," the Pirates kept their focus off the scoreboard.
"If you get too caught up in the score or too caught up in things that are out of your control it's going to lead to pressing and trying to do too much," Walker said. "We do a good job of not doing that around there."
Pittsburgh responded in the home second with three consecutive hits leading off the inning. First baseman Gaby Sanchez led off with a single then Walker reached on a hit to right and took second when Colorado right fielder Carlos Gonzalez threw to third as Sanchez got in safely.
The extra base taken by Walker set up a two-run single by Mercer, pulling the Pirates within 3-2.
"We're going to be aggressive," Walker said. "We're going to get thrown out, we're going to look stupid at times, but at the same time we're going to make aggressive plays that lead to runs. Some people may call it stupid, we call it aggressive."
Mercer thought he scored the game-tying run on a Stewart double down the left-field line but was sent back to third by the umpires as the ball stuck under padding lining the wall.
Pittsburgh left-hander Jeff Locke worked six innings and gave up three runs on seven hits and two walks.
"I don't think there's a lot of games you can pitch the way I pitched today and come away with a win at the end of the day," Locke said.
Colorado starter Tyler Matzek worked through six innings for the fifth consecutive start, and posted a quality start for the fourth time out of his last five outing.
Pittsburgh tied the game against Matzek in his last frame when catcher Chris Stewart bounced his second double of the game into the left field bleachers that scored shortstop Jordy Mercer from second.
Matzek allowed three runs on seven hits, walked three and struck a career-high eight hitters.
"Tyler did a great job," Weiss said. "Put us in position (to win) again. That's three good starts in a row by our starters but couldn't get the big hit to bust it open early."
Matt Belisle (2-6) entered to work the seventh and was unable to finish the inning, leaving after he recorded two outs and was charged with two runs. He walked the leadoff man, Josh Harrison, who stole second and scored on McCutchen's single.
After McCutchen was caught stealing for the first time this season, Walker homered to center.