JUPITER, Fla. -- There was a time early last season, when Alex Reyes allowed just four earned runs while saving his first 20 games, that the closer finally found his groove and was pitching to the level he always thought he could reach.

Then, just like in 2016, ’18 and ’19, pain returned to wreck Reyes' run and leave him wondering if he will ever be healthy enough to fulfill the vast potential set for him years ago, when he was one of the top prospects in baseball.

Reyes’ pursuit of that dream will be put on hold again after an MRI revealed that he has a frayed labrum in his right shoulder, an injury that requires a stem-cell injection. He won’t throw a ball for the next four weeks, and he’ll likely miss the first two months of the season as the shoulder heals and strengthens.

Just as Reyes thought he had finally turned the corner on his injury history, he’s back in the rest/rehab/return cycle again.

“I think last year, in the beginning of the season, I pitched to my ability,” Reyes said on Saturday morning in the Cardinals' locker room at Roger Dean Stadium. “There was room for improvement, and I think everyone saw that. For me, it’s just about managing my body. That’s going to be tough through the years to come, but I’m trying to find ways to stay on the field. The best ability is durability, and unfortunately, I haven’t been able to show that.”

Reyes’ injury, combined with the shoulder pain that has delayed 2020 and ’21 Opening Day starter Jack Flaherty, has the pitching staff a bit in flux. Staff ace Adam Wainwright is seemingly in line to make the sixth Opening Day start of his career, while Miles Mikolas, Steven Matz and Dakota Hudson fall in behind. Mikolas, who missed time last season with tendon trouble in his elbow, will start on Sunday, when the Cardinals face the Mets in Port St. Lucie.

• Notes: Flaherty (shoulder) out for 2 weeks

The No. 5 spot is where things get fuzzy. John Woodford, Johan Oviedo, rookie Matthew Liberatore, and newcomers Aaron Brooks and Drew VerHagen are candidates for the job until Flaherty is healthy enough to return. New manager Oliver Marmol said on Saturday that he would prefer to take five set starters to St. Louis instead of using various relievers to fill one of the slots on the fifth day through the rotation.

“It becomes a nice competition for the guys in camp to determine who is going to step up and take that spot in the rotation,” Marmol said. “I’m looking forward to seeing it.”

There is a bit of a disagreement between the Cardinals and Flaherty over the source of his shoulder pain, which required a platelet-rich-plasma injection to calm the inflammation. Team president John Mozeliak said on Friday that tests revealed Flaherty has “a SLAP tear, a small tear,” which prompted Flaherty to tweet “LOL.” Flaherty later went on Instagram and said, “I don’t get why this was said as if it was something new. I have pitched with [the SLAP tear] for years. This isn’t the first time it was seen. No reason to bring it up now.”

SLAP refers to the superior labrum anterior and posterior cartilage-like material around the shoulder socket.

Marmol hopes to have Flaherty back on the mound soon. Flaherty, a nine-game winner a season ago, is scheduled to go through salary arbitration in the coming weeks, and his injury history could affect his earnings potential.

“We just texted back and forth, and ... we’ll figure out what the approach is once he gets back in-house,” Marmol said. “We want him to feel comfortable about the plan moving forward. That’s the most important thing.”

The most important thing now for Reyes is to get healthy and find a way to salvage a career that has been slowed by elbow and labrum (twice) injuries. Last season he made his first All-Star team after posting a 10-8 record with 29 saves. But when the shoulder troubles popped up, he blew five saves, lost his closer role and was on the mound when the Dodgers walked the Cardinals off in the playoffs.

Reyes' pain lingered through the offseason until he finally shut down his throwing routine two weeks before Spring Training. All things considered, he thinks he’s lucky that he will be able to pitch again soon and hopefully regain his form from early 2021.

“For me, it’s a huge positive that this doesn’t include any surgery or anything like that,” Reyes said. “I’ve been through so much, and [surgery] is what I’ve always feared the most.

“My goal is to get healthy and be ready to pitch, wherever it is, and help my team win a championship.”