SURPRISE, Ariz. -- The Angels’ bullpen competition is a bit murkier after right-hander Aaron Slegers was scratched from pitching in a "B" game with back issues on Thursday. It came after righty Felix Peña was diagnosed with a right hamstring strain that is likely to keep him off the Opening Day roster.

Slegers and Peña were both strong candidates to make the bullpen, and now it could open the door for others to possibly make the club. Interestingly, manager Joe Maddon said the Halos could consider prospects Reid Detmers or Chris Rodriguez in a bullpen role. It doesn’t appear very likely, but they’ve both pitched well this spring. Rodriguez, ranked as the team’s No. 4 prospect by MLB Pipeline, is considered more likely to make the club over Detmers (ranked No. 2) because his stuff plays up better as a reliever.

“Sometimes you have a long-term vision for somebody as a starter, but out of necessity other things occur,” Maddon said. “Everybody's always worried about guys getting hurt. But I think if you don't worry about it, a guy could blossom from [that role]."

Maddon said it wasn’t unusual for teams to use their top pitching prospects in relief before being converted back to starters, citing players such as Brandon Woodruff, Chuck Finley and Chris Sale as examples. But Rodriguez has had back injuries that have limited him to 9 1/3 professional innings since 2017, so the club would have to be cautious with him.

“You’d have to be prepared to be frugal between his appearances,” Maddon said. “And make sure he has time to recover. You can’t get greedy with a guy like that.”

Right-hander Jaime Barria is also still waiting to hear if he’ll have another year of options, which will also affect the Angels' decision. If Barria has options, he’ll likely be stretched out to start at the alternate training site, but if he doesn’t, he’ll make the Major League roster as a reliever.

Non-roster invitee Jake Faria could make the roster as a long reliever, while the Angels also haven’t ruled out Patrick Sandoval making the club as a lefty reliever. They would prefer for Sandoval to get stretched out as a starter, but he could make the team out of necessity.

Rule 5 Draft pick Jose Alberto Rivera, a right-hander, was late to camp, which has limited his exposure to the coaching staff. He’s not expected to see enough action to make the club. Rivera will have to be placed on waivers, and if no team claims him, he must be offered back to the Astros for $50,000.

“It’s difficult for him right now,” Maddon said. “I’m not saying it’s impossible. It’s just difficult.”

Maddon added that there’s still a chance Slegers will make the roster, as he was feeling better on Friday. But it’s something they’ll monitor over the coming days.

"I don't think we're there yet, today's always the big day,” Maddon said. “And he's responding pretty well. So let's give it a brief period of time forward from here and see where he's at."

Bundy solid yet again

Right-hander Dylan Bundy, who was named the Halos' Opening Day starter on Monday, continued his strong spring, allowing two runs (one earned) on three hits over five innings. He struck out six and has a 0.77 ERA in 11 2/3 innings this spring.

"Felt good today," Bundy said. "Body is feeling good. Overall, with all my pitches, I felt better. I was working on the curve and slider in between starts. I still got one more start to fine-tune. I still gotta work on fastball command. But I’m excited to get the ball rolling."

Bundy, though, was hurt by a defensive miscue from center fielder Jo Adell in the fourth. Bundy surrendered a deep drive to center off the bat of Carlos Santana, but Adell lost track of the ball at the wall and it dropped in for what was ruled a two-run ground-rule double. Adell appeared to lose the ball in the sun.

"It was a tough spot," Maddon said. "He kind of lost sight of it."

Angels tidbits

• Reliever Luke Bard also isn’t expected to be ready for Opening Day, as he’s been out with right hip discomfort. Bard could open the year on the injured list or be optioned to the alternate training site if he’s healthy before the start of the regular season.

• Infielder José Rojas continued his strong spring, going 2-for-2 with a double off the left-center-field wall and a walk. He’s batting .400 (8-for-20) in Cactus League play and could make his debut this season.