BALTIMORE -- Four consecutive starts have turned Bruce Zimmermann’s season from a sensation to a bit of a search.

That was the trend Zimmermann acknowledged existed prior to -- and then was further exacerbated by -- Friday’s series-opening 6-3 loss to the Guardians at Camden Yards. The lefty, sporting a tweaked delivery and windup after fears of pitch-tipping, was hit early and often before rebounding for a calmer end to the night.

All told, with Cleveland rattling off 10 hits and five earned runs against him, Zimmermann has now allowed 20 earned runs across his last four starts compared to just 11 in his first seven.

He’ll take some solace that he retired 10 of his last 13 batters -- but only a bit.

“Saw some good things, but I'm obviously not too excited with the results,” Zimmermann said. “I'm kind of a perfectionist.”

It also didn’t help Zimmermann or the Orioles writ large that they were no-hit by Cleveland ace Shane Bieber for 5 2/3 innings, and nearly shut out by him in seven-plus.

With Friday’s domination (seven-plus innings, 11 strikeouts), Bieber had pitched 24 frames against Baltimore across three starts in his career without allowing a run before Trey Mancini’s two-run double broke the Orioles through off Bieber … after he had exited the game.

“That's as dominating as I've seen here in a while,” Orioles manager Brandon Hyde said.

But even a more modest showing wouldn’t have done much to rectify the day. That’s the unfortunate reality the Orioles have endured as Zimmermann has struggled to replicate his early-season success in recent outings.

And much of that can be attributed to a single pitch.

Zimmermann’s changeup is his most leaned-upon weapon, at times leading the Majors in whiffs. As his changeup goes, so have his starts -- especially recently. Take his changeup usage in his first three starts of the season, for example, during which Zimmermann owned a 1.20 ERA and 2.88 FIP, putting him near the top of the list of early-season surprises:

• April 11 (4 IP, 3 H, 0 ER, 0 HR): Two whiffs on seven swings
• April 17 (5 IP, 4 H, 0 ER, 0 HR): Eight whiffs on 17 swings
• April 22 (6 IP, 5 H, 2 ER, 1 HR): Five whiffs on 12 swings

And in his last four starts, after which his ERA sits at 4.87:

• May 19 (5 IP, 7 H, 5 ER, 1 HR): One whiff on nine swings
• May 24 (6 1/3 IP, 6 H, 4 ER, 4 HR): Two whiffs on 15 swings
• May 29 (4 IP, 8 H, 6 ER, 5 HR): One whiff on 13 swings
• Friday (5 2/3 IP, 10 H, 5 ER, 0 HR): Zero whiffs on 17 swings

The Guardians totaled six of their 10 hits off of Zimmermann’ changeup, including both of Owen Miller’s two run-scoring swings that staked Cleveland to a 4-0 lead in the third inning.

“I think the only time I'm getting hurt with that changeup is when it's up in the zone, which it's been a little bit more up as of late,” Zimmermann said. “The back half of this outing, I was able to establish it at the bottom of the zone and through the bottom of the zone, and able to play that one-seam [sinker] off of that. … I kind of wish I had done that from the get-go today.”

“The changeup didn't have the depth that it had earlier in the season,” Hyde added. “Something to work on, but I thought he did pitch better as the game went on.”

Zimmermann will also take Friday with a grain of salt. Following his last two outings in New York and Boston, during which he allowed nine home runs, Zimmermann met with the Orioles’ pitching brain trust, fearing that he was tipping something off the mound. That resulted in a different delivery on Friday evening -- something Zimmermann will continue to work with, knowing it’s difficult to implement such a stark change in one go.

“Tough to get used to in one start,” Zimmermann said.