Astros’ pitching staff delivers; Padres up next

HOUSTON — Having rolled to four consecutive victories without yet encountering any high-leverage innings where a reliever faced anything resembling a save situation, the Houston Astros faced such a scenario on Wednesday in the finale of their three-game set with the Baltimore Orioles.

After one turn through the rotation, Houston relievers took a back seat to a starting quintet that posted a 1.78 ERA after five games. But with left-hander Dallas Keuchel laboring through an inefficient outing undermined by shaky defense, the Astros needed their bullpen to deliver.

Right-handers Hector Rondon and Brad Peacock combined to post four shutout innings, with Peacock picking up the win in relief by working the seventh, eighth and ninth in dominant fashion. The Astros (6-1) will open a three-game interleague series against the San Diego Padres on Friday at Minute Maid Park fresh off the experience of their bullpen acing its first true test.

“I think our bullpen is evolving,” Astros manager A.J. Hinch said. “We haven’t quite synced into the normal usage or when guys are going to pitch. I think I’m learning that we have a lot of different weapons that I’m going to have to learn how to maximize.

“Certainly, if our rotation pitches into the sixth and seventh inning routinely like they have over the first week, that changes in terms of their usage pattern.

“What I like about our bullpen is they have really good stuff and they match up specifically to certain styles of hitters. And the more we learn about the new guys, Rondon and (right-hander Joe) Smith, and mix where (the holdovers) fit, I feel like we’ve got a versatile enough bullpen to be extremely effective.”

Right-hander Lance McCullers (1-0, 3.38 ERA) will start for the Astros on Friday. He posted 10 strikeouts in his season debut against the Texas Rangers, allowing two runs, four hits and one walk in 5 1/3 innings.

McCullers has never faced the Padres, with whom his father Lance Sr. spent four seasons (1985-88) while compiling a 21-28 record with 36 saves and a 2.96 ERA.

McCullers is 2-0 with a 2.73 ERA in five interleague starts against the National League.

Right-hander Luis Perdomo (0-1, 11.25 ERA) will start the series opener for the Padres (1-6). Perdomo endured a rough opening to his third season with San Diego, allowing five runs, seven hits and four walks with seven strikeouts in four innings against Milwaukee on March 31. The 24-year-old Dominican has never faced the Astros and has made nine interleague appearances, going 3-2 with a 6.10 ERA in seven career starts against the American League.

San Diego capped its season-opening, seven-game homestand with a 3-1 loss to Colorado on Thursday, its third setback in four games against the Rockies. Rookie left-hander Joey Lucchesi produced a promising start for San Diego, surrendering a leadoff single to Charlie Blackmon in the first but no additional hits through five innings. Lucchesi fanned seven batters.

The Padres would welcome a similar performance from Perdomo, who had just one scoreless outing last season. On June 23 against the Detroit Tigers, Perdomo allowed two hits and five walks with six strikeouts in six scoreless innings while posting a 1-0 victory at Petco Park.