SAN DIEGO -- Whenever the Padres open their 2020 season, they will be forced to do so without hard-throwing righty relief weapon Andres Muñoz.

The 21-year-old, who averaged 99.9 mph on his fastball last season, underwent Tommy John surgery on Friday. He will miss the entirety of the '20 campaign, which, of course, has already been delayed due to the coronavirus pandemic.

San Diego already boasts a deep group of bullpen options aside from Muñoz. But his ceiling was unquestionably high, with some in the organization touting him as a potential closer of the future.

That's still possible. But in the short term, the Padres might call on these three bullpen arms to step up in Muñoz’s absence.

Javy Guerra
If there's one pitcher in the Padres' bullpen whose skill set is closest to Muñoz's, it's Guerra. Sure, Guerra is three years older, but his upside is similar to Muñoz, mostly because he only began pitching a season ago after making the transition from shortstop.

They're both right-handers with big fastballs. (Guerra's is a two-seamer that sits between 98-99 mph.) They both complement that fastball with a tricky slider to keep hitters off balance. And they're both young enough that they're still working through some issues with command and control.

Upon his September callup last season, Guerra was knocked around a bit, but he's evolved since then. He's stopped throwing his flat four-seamer and turned to a two-seamer with significant tail. He used that pitch to great success this spring, posting 5 1/3 scoreless innings.

At this point, Guerra is basically a roster lock. He's out of options and the Padres wouldn't risk losing an electric arm like his. With Muñoz out of the equation, however, Guerra’s role might have become a bit more important.

Cal Quantrill
Matt Strahm and Drew Pomeranz have started in the past, but it's clear by now that their true value lies in the bullpen. They’ll work two or three innings on occasion, but their stuff clearly plays best in relief.

Of course, if we're discounting Strahm and Pomeranz, that leaves the Padres without a true swingman in their bullpen. That's where Quantrill comes into play. Muñoz’s absence might just clear space for Quantrill to be on the Opening Day roster.

When camp was halted last week, Quantrill was on the outside of both the rotation and bullpen races -- but not by much. He'd posted seven innings of one-run, two-hit ball while striking out nine. If that type of performance continues, the Padres might be forced to find a place for Quantrill.

The 25-year-old right-hander could still supplant Joey Lucchesi for the No. 5 spot in the rotation, but there's probably a better chance he makes the team as the eighth man in the bullpen and a potential spot starter.

José Castillo
The Padres constructed a deep, loaded bullpen to combat the usual year-to-year volatility. They didn't expect this injury, but they expected injuries. So, in some ways, they were prepared for this.

"We have some bullpen depth," Padres general manager A.J. Preller said. "But in general, with pitching, you know you need as many arms as possible, because injuries are unfortunately a part of it."

There's one easy way for the Padres to replace Muñoz’s production: They could get it from a healthy Castillo. The left-hander missed nearly all of the 2019 season with a pair of injuries to his forearm and middle finger.

Castillo is a lefty with a different skill set than that of Muñoz, but his stuff is equally as filthy. In 38 career appearances, Castillo owns a 3.23 ERA with 54 strikeouts in 39 innings. That kind of production would go a long way toward making up for the loss of Muñoz.