BALTIMORE -- The Orioles have a hole in their rotation. That was made glaringly obvious when right-hander Spenser Watkins landed on the injured list with a right elbow contusion. And that reality was chief in the calculus of recalling lefty Zac Lowther ahead of Tuesday's 10-0 series-opening loss to the Mariners at Camden Yards, where he pitched bulk innings behind opener Bryan Baker.

The organization is evaluating its 40-man roster, looking across the system for inning-eaters. Lowther was given the chance to try and inch his way up the conversation. He had to fight through two difficult innings for four of the more breezy variety, part of an evening that took the air out of the tires of a remarkable prior four days in Boston.

“The third inning, I didn't know what we were going to do,” said manager Brandon Hyde, “because if [Lowther] wasn't going to last very long, I was going to throw a bunch of guys that I didn't want to throw in a game like that. … That was big.”

Whether Lowther remains in Baltimore or returns to Triple-A Norfolk may be telling in how the Orioles view this slight impasse of innings. The most intriguing question they face is if top pitching prospects Grayson Rodriguez and DL Hall soon plug the void. But if they need innings, here are some options:

Lowther
Across his first 1 2/3 innings, Lowther allowed nine of the 14 batters he faced to reach base. Across his last four frames, he allowed just three of 14. It was a very nice bounce-back for the Orioles’ No. 27 prospect, who needed it.

“I came out of the bullpen a little too hot and mechanics were all out of whack,” Lowther said. “... Just trying to be who I am and not too much, not too little. Just find that sweet spot and perfect that.”

Hall
Hall, Baltimore’s No. 5 prospect, pitched in unison with the big league club on Tuesday night, striking out six for Triple-A Norfolk across three innings. It was Hall’s seventh start of the season and fifth at Norfolk, bringing his ERA there to 4.86, having allowed two runs in his latest go.

There are some areas Hall needs to sharpen before talk of a promotion becomes more serious. The first are the walks; he allowed two free passes on Tuesday, bringing his total to 11 across 16 2/3 Triple-A innings. That’s a 14.86 percent walk rate and a 5.94 walks per nine -- the latter of which is just a hair under the 6.0 full-season career high he owned in 2019.

The other is health. Hall, coming off an injury-stunted season, has been limited to no more than four innings/60 pitches per game in 2022. He’ll need to be stretched out more in full -- and for a prolonged period of time -- before any debut.

Rodriguez
Someday soon, Camden Yards might see Hall and Rodriguez pitch on consecutive days. Norfolk will see that this week.

Rodriguez will take the ball for Norfolk’s tilt on Wednesday as he makes his 11th start of the season; he's already up to 50 1/3 innings. His last might have been the best of his career, with 10 strikeouts across seven shutout frames, allowing just two baserunners.

Rodriguez already entered the week among the best in the Minor League circuit in many statistical categories, including first in FIP with a 1.60 mark. He’s making it hard not to push the question more seriously of a callup, but only topping out at 88 pitches thus far, it’s likely the Orioles will want to give him a little more runway at full-go before he reaches Baltimore. That’s what executive vice president and general manager Mike Elias hinted at recently.

LHP Nick Vespi
Perhaps the best-performing arm at Triple-A who’s already debuted, Vespi would seem to have a solid niche on the current roster, a secondary hard-throwing lefty behind Cionel Pérez. It appears Vespi’s return for a more solidified role is just a matter of time; he’s allowed zero earned runs across 19 1/3 innings for Baltimore and Norfolk this season.

RHP Michael Baumann
Sent to Triple-A in order to work in a more controlled environment, Baumann is still searching. He has allowed 10 earned runs across 13 2/3 innings in Triple-A this season, three of which came for Norfolk on Tuesday night. He could be back in a pinch when eligible, but the O’s will likely give him time to rediscover himself, still, in some ways, making his way back from an injury-marred 2021 that saw him throw just 70 2/3 innings.

RHP Cody Sedlock
Sedlock impressed mightily over his long-awaited Major League debut on May 29 for the first three innings. The O’s pushed him for a fourth, which is when the floodgates opened, but he did much to earn himself more consideration for innings as the season progresses.

RHP Chris Owings
OK, not actually. But it was Owings who took the title as the O’s first position player called to the mound this season, tasked with the ninth inning as the Orioles faced a nine-run deficit. He, of course, was met by Adley Rutschman on the foul line when he wrapped up his inning.