MESA, Ariz. -- Adbert Alzolay expected to come into camp this spring, earn one of the Cubs' rotation spots and prove this season that those bursts of promise in the past were signs of a pending breakout performance.

That has all been put on hold now for Alzolay, who felt tightness under his right arm roughly three weeks ago. The Cubs pitcher is currently shut down due to a shoulder strain that involves his lat muscle, requiring a month of rest before picking up a baseball again.

"It's just very disappointing at this point," said Alzolay, standing at his locker on Tuesday morning. "I feel that all the work that I have put in this offseason, it just got wasted in the end, pretty much."

It is a setback that has thrown another wrinkle into the Cubs' rotation plans, which were already complicated behind the veteran trio of Kyle Hendricks, Marcus Stroman and Wade Miley. The rest of the options are lean on Major League experience and the short runway to Opening Day adds another layer to the situation.

What does this mean for Alzolay?
Alzolay noted that this shoulder injury is similar to the one that he sustained as a Minor Leaguer in 2018. That season, the righty did not pitch after May. This time around, Alzolay is hopeful that he can return within a couple months.

"I just feel that whenever I'm ready," Alzolay explained, "[in] one month, two months, I can help the team either coming out of the bullpen multiple innings or being a starter."

Last year, Alzolay had a 4.58 ERA in 29 games (21 starts) with 128 strikeouts against 34 walks in 125 2/3 innings.

It should be noted that the Cubs have not put a timetable on his return. All president of baseball operations Jed Hoyer would say was that Alzolay would open the season on the injured list, and it would not be a "minimum stay" on the shelf.

Where does righty Alec Mills fit into the picture?
Nothing is carved in stone, but Cubs manager David Ross said Tuesday that Mills has earned the right to head into Spring Training as a part of the rotation. That puts him in prime position to claim one of the vacancies.

"We're going to plan for Millsy to be a starter," Ross said. "If something changes, we'll adjust from there. But, yeah, I think he's proven he deserves a shot at being in the rotation, for sure."

Mills, 30, has bounced between the rotation and bullpen for a few seasons now, but his performance has been better on a starter's routine. The righty has a 4.45 ERA in his career out of the rotation, compared to a 5.24 ERA as a reliever.

What are the other in-house options?
Last season, the trio of Alzolay, Justin Steele and Keegan Thompson gained MLB experience both out of the rotation and in the bullpen. As camp opens, Steele and Thompson will be in the mix for one of the rotation jobs.

That said, Steele and Thompson also found success as multi-inning relievers for the Cubs last year. Given the shorter spring schedule, pitching coach Tommy Hottovy noted that there could be "piggyback" outings, if starters are not stretched out all the way. Steele and Thompson could fit that mold as hybrid options come Opening Day.

"Whatever they want me to do this year, I mean, I've already done it," Steele said. "So, I'll be comfortable in any role."

Who could help from the farm system?
Righty Cory Abbott had a taste of the Majors (seven games) last season and piled up 130 strikeouts in 96 innings in his time with Triple-A Iowa in '21. He is another option on the 40-man roster who could be in the mix for rotation innings or in a multi-inning relief role this season.

Right-hander Caleb Kilian, the Cubs' No.14-ranked prospect, per MLB Pipeline, is not on the 40-man roster, but has a chance to reach the Majors this year. Acquired from the Giants in the Kris Bryant trade last year, Kilian had a 2.42 ERA with 112 strikeouts and 13 walks in 100 1/3 innings between High-A and Double-A last year.

Will the Cubs look to add another starter?
Ross made it clear on Tuesday that the Cubs' front office was still on the hunt for rotation help. Even without the setback with Alzolay, Chicago was going to need to add innings in any way, shape or form before Opening Day.

"They're still intent on getting more pitching," Ross said. "That'll shape out more, even for me, as we get things filled out."