PEORIA, Ariz. -- The Padres spent their offseason constructing a deep bullpen with a few electric arms at the back end.

That depth, it seems, is going to get an early test. Because another one of those electric arms is likely to open the season on the injured list.

Right-hander Robert Suarez is experiencing joint inflammation in the back of his right elbow and is expected to begin the year on the IL -- though he recently underwent testing, including an MRI that revealed no structural damage. The Padres are viewing Suarez’s early absence as a precaution, hoping their proactive step of holding him out early will better sustain him for the long run of the season.

"We're being really cautious with him, for obvious reasons," said Padres manager Bob Melvin. "We don't want to get him off to a start where he's feeling it and we can't use him back-to-back days or it's something that lingers. We want to knock this out right now, and I know he's feeling a lot better right now." 

Suarez, who signed a five-year, $46 million contract to remain with San Diego in the offseason, posted a 2.27 ERA last year. But he was limited to 45 appearances, as he missed two months midseason with a knee injury.

The right-hander would join lefty Drew Pomeranz on the IL -- two potential setup options for closer Josh Hader. The Padres are hopeful that neither absence will be prolonged (and, on that front, Pomeranz threw a bullpen session Saturday as he continues to build his way back from 2021 flexor tendon surgery in his left elbow).

Here are a few more details on Suarez's injury:

What's the nature of the injury?
Suarez made four appearances this spring, allowing two runs over four innings. But he hadn’t pitched since March 12.

Suarez's throwing progression has slowed, with the soreness typically occurring the day after he throws, a source said. The team is viewing Suarez’s early absence as a proactive measure to get him on the right track when he debuts.

He would be eligible to return from the IL on April 11, with the team able to back-date his IL stint to March 27.

How do the Padres replace Suarez?
Even with Pomeranz and Suarez unavailable, the Padres have options for the eighth inning.

Righty Luis García and lefty Tim Hill would presumably step into that primary setup role -- potentially alternating based on the handedness of the opposing hitters.

But Suarez’s injury would have a clear knock-on effect, perhaps leaving the sixth and seventh innings uncovered. Steven Wilson is one option for high-leverage work. Do-everything swing-man Nabil Crismatt is another.

After that group, two places are available in the San Diego bullpen. Jay Groome, Brent Honeywell Jr., Julio Teheran and Ryan Weathers are all vying for the No. 6 starter spot. But it’s possible the Padres would keep two from that group as long relievers.

What's the state of the Padres' bullpen depth?
Certainly not as deep as it was entering camp. Lefties Adrian Morejon, José Castillo and Pomeranz and righties Craig Stammen and Suarez are likely all out of the Opening Day roster discussion due to injury. That’s an impressive group of arms that will be unavailable to start the season. (Castillo, like Pomeranz, threw a bullpen session on Saturday as he works his way back from a shoulder issue.)

Keep an eye on right-hander Domingo Tapia, who has a 2.25 ERA with 11 strikeouts in eight innings this spring. Tapia, a non-roster invitee, was a longshot for the Opening Day roster at the start of camp. He probably still is, considering the Padres’ bullpen could use some length. But Tapia’s odds are increasing with each injury (and each quality outing he turns in. Tapia pitched a 1-2-3 eighth on Saturday, striking out two Rangers).