HOUSTON -- A road trip defined by close finishes and organizational parallels ended on a flat note Sunday for the Orioles, who capped their tour through the heart of Texas with a 4-0 loss to the Astros at Minute Maid Park.

A weakness for most of the year, the Orioles’ rotation excelled this week in notoriously hitter-happy environments, posting five quality starts in six games against the Astros and Rangers.

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“I thought it was our best series of the year from a pitching standpoint,” said manager Brandon Hyde, whose hurlers held the Astros to eight earned runs over 27 innings this weekend. “It’s very encouraging going forward.”

The culprit again Sunday was the offense, which stayed dormant for much of the afternoon opposite old friend Wade Miley, then saw a bases-loaded, no-out threat stamped out by uber-reliever Ryan Pressly in the seventh.

That was enough to waste another strong effort from Dylan Bundy, and send the Orioles to their 12th series defeat in their past 13 tries, dating back to late April.

“It’s frustrating, but I think we’re playing better baseball and we’re staying in games,” Bundy said. “I thought we were pretty consistent this whole road trip and gave our team a chance to win pretty much every night out.”

Bundy made just one costly mistake Sunday: A 1-0 changeup that Astros rookie Yordan Alvarez deposited over the left-center field wall for his first career homer, a two-run shot that broke a scoreless tie in the fourth. Richie Martin’s throwing error also opened the door for an unearned run in the sixth, and Yuli Gurriel’s sac fly stretched the lead off Evan Phillips in the eighth.

Besides that? Bundy scattered three singles and struck out six over six innings.

From John Means on Wednesday to Andrew Cashner on Saturday to Bundy and beyond, Orioles starters posted a 3.34 mark on the trip, during which the club went 2-4. Consider it progress for a unit that left Baltimore last weekend with a 5.68 collective ERA, the highest in the Majors.

“It would mean everything [if that continued],” Hyde said. “I love the way our starters are throwing the ball, and getting deep in the game. I was really encouraged by our bullpen this series. I thought we pitched great this series. I thought it was our best series of the year from a pitching standpoint. It’s very encouraging going forward.

Here are a few more takeaways from Sunday’s finale:

Bundy’s evolution continues

Is Bundy emerging as the Orioles’ best trade chip? That would’ve seemed unlikely just a month ago when Bundy, coming off a career-worst 2018, dragged an ERA north of 6.60 into the month of May. But his adjustments since have been plain to see, and should they continue, could boost the stock of the former top prospect, who is under team control through 2021.

Those adjustments have come mainly in regard to his pitch mix. Bundy has morphed into one of the American League’s more consistent starters since adjusting his fastball usage over the past six or so weeks ago. Though Sunday was an exception, he’s still thrown fewer than 50 percent heaters in four of his past six starts -- a notable departure for a pitcher who has been ultra-heater reliant for much of his career.

“His secondary stuff is really good and it’s letting his fastball play,” Hyde said. “He’s competing. I love the look from him out on the mound, and he’s giving us a chance to win every time out. He’s doing a great job.”

On Sunday, Bundy reverted briefly -- using the fastball 58 percent of the time and allowing just two singles with the pitch. But in the aggregate, the numbers hold. Bundy threw 53 percent heaters before May 1, pitching to a 6.67 ERA and .951 opponent OPS in those outings. Since? He’s thrown just 45.8 percent, bumping his slider, curveball and changeup usage. The result: An ERA of 3.02 over his past seven starts.

International vibes

With their revamped international scouting operation under new senior director Koby Perez, the Orioles are hoping to eventually compete at the top of the market for prospects like Alvarez, whom the Dodgers signed out of Cuba in 2016. Alvarez was in Houston’s system two months later, acquired via trade by a front office featuring current Orioles executive vice president and general manager Mike Elias, and on a fast track to the Majors. The 21-year-old Alvarez was leading all Minor League hitters in home runs prior to his callup Sunday, when he homered off Bundy in his second big league at-bat. The 413-foot two-run shot to left-center broke a scoreless tie in the fourth.

The Orioles plan to announce a slew of international signings early next month, which Elias recently teased as “the largest” class in franchise history. None are expected to be as highly touted as Alvarez, given the years of advance work required to make inroads internationally. But in time, the hope is that the Orioles become an attractive destination for prospects of his caliber. Sunday provided another example of the return on investment often seen by clubs that already are.

Fun with numbers

In setting his lineup for Sunday’s finale, Hyde snapped a wacky streak. He’d been the only manager in baseball yet to repeat a lineup this season, using 64 different permutations for the Orioles’ first 64 games.

“I think it was more of a media curiosity,” Hyde said. “That was definitely not my goal to come in and change it up all the time.”

It was, Hyde said, more a byproduct of Baltimore’s oft-changing roster and the rookie skipper’s consistent search for platoon advantages. The Orioles have already cycled through 42 players this season, and feature quasi-platoons in at least four positions for the time being. That’s led to an inordinate number of mixing and matching. Expect it to continue.

“I think at some point we’ll have more of a set lineup,” Hyde said. “Looking forward to that day. But right now where we are, you’re going to see a lot of different lineups.”