Who will fill out the bullpen? 

MESA, Ariz. -- A strength of the club in 2020, the Royals bullpen returns the core of its relievers this season, specifically the high-leverage relievers in Scott Barlow, Jesse Hahn, Greg Holland and Josh Staumont. Barring injury, they figure to appear in the later innings and close games, and manager Mike Matheny could find a traditional closer to rely on as the season progresses and roles become more defined.

The Royals have a deep well of arms that could fill out that bullpen come the regular season and even more arms at the alternate training site before the Minor League season begins. Spring Training has been about finding the right mix, factoring in versatility and different looks that Kansas City could have. Some decisions have already been made -- the Royals optioned right-hander Tyler Zuber to Triple-A on Tuesday. Zuber debuted last year and flashed potential, but he struggled with walks and attacking hitters in the zone.

“There are a couple of things that he was doing mechanically that were taking him away,” Matheny said. “He’s fixing them, and he’s heading in the right direction. The unfortunate thing is, we’re running out of innings to get those repetitions with us. 'Here’s the truth, here’s where we need you to get, and hurry up and get there. And stay ready because you’re somebody that we trust. There are just some things that have to be fixed.'

“It’s already tough. We’re going to have to keep watching the team as a whole.”

Here’s a look at some arms the Royals are watching for an Opening Day spot in the bullpen:

Wade Davis, RHP
After signing a Minor League deal with the Royals, Davis needed to show health and command after two shaky seasons with the Rockies. That’s exactly what he’s done this spring, with an uptick in velocity and life to his fastball. He hasn’t allowed a run in five Cactus League innings, holding hitters to a .188 average, and he’s looked just as sharp on the backfields.

Carlos Hernández, RHP
The Royals’ No. 11-ranked prospect, per MLB Pipeline, Hernández has developed as a starter but could find a home in the bullpen this year based on his stuff and versatility. Matheny tested Hernández on Tuesday night by having him enter the game in the middle of the fourth inning, and Hernández got two quick outs to end the frame before allowing one home run in the fifth. The 24-year-old has plus stuff, including a fastball that routinely hits 100 mph. A curveball and slider give him a good mix as a reliever if he does end up there.

“The fact that he felt ready to rock and his adrenaline was going, those sort of things for a young player who hasn’t been in that situation before, it’s just good to see,” Matheny said. “Part of the test is how he feels [Wednesday]. But he’s in this conversation.

“This is a guy who could pitch multiple innings for you. Could do it at the beginning of the game, or, with the kind of stuff that he’s throwing right now, he could end the game for you.”

Jakob Junis, RHP
Another versatile arm, Junis is being stretched out to be a potential swingman for the Royals, starting some games and relieving others. A new cutter gives him another weapon as a starter, but the Royals also like what he brings as a reliever. He has given up one run in five Cactus League innings, but has gotten his most recent work in B games.

Kyle Zimmer, RHP
It’s been a long journey for Zimmer, a first-round MLB Draft pick who has pushed through an injury-plagued career and finally found his footing in '20, with a 1.57 ERA in 23 innings (16 games). He’s coming off a healthy offseason, giving him a different outlook this year and more confidence this spring. Zimmer worked his way into a more prominent position in the bullpen, earning the trust of the coaching staff to appear in higher-leverage situations.

“Just coming off the success of last year, knowing that one, I’m healthy, and two, my stuff plays at the level I want to be striving and succeeding at,” Zimmer said. “I think that helped going into the training and just having that confidence coming into this camp hungry to get better.”

Zimmer’s task this year will be to carry his success over to a 162-game season -- and stay healthy through it, too.

“Bottom line, just getting your body in the best place that it can be to be available every single day,” Zimmer said. “That’s my goal. to be able to go out there every day and compete and let them know I’m good to be used on a daily basis.”

Brad Brach, RHP
Another non-roster invite, Brach is showing the Royals what he could bring to their staff this spring with his funky delivery and intriguing mix of pitches.

Location was the issue for him on Tuesday night, when he allowed five runs in one-third of an inning, but the Royals aren’t going to define his career with one outing. The right-hander will continue to get innings this spring as the Royals decide whether he’ll break camp with them.

Richard Lovelady, LHP
The Royals didn’t have a left-handed reliever they could rely on last year, which wasn’t as big of a deal because of the three-batter minimum -- and because Royals righties were effective against left-handed batters. But there are two lefties who could give the Royals that lefty look in the bullpen: Lovelady and Jake Brentz.

Lovelady is on the 40-man roster and hasn’t allowed a run in 4 2/3 innings this spring despite being called upon to get the Royals out of messes.

“Last year we had righties with effectiveness against lefties that would probably be better than most lefties effective on lefties,” Mathney said. “We need to see if that continues in the right direction. But I also think we have a couple good internal options. I’ve been very impressed with Richard Lovelady and Jake Brentz, both guys who have thrown the ball exceptionally well.”

Brentz, LHP
Brentz, a non-roster invite, is somewhat of a darkhorse here because of his journey through three organizations before signing with the Royals in '19, but he has been a camp standout over the last few weeks. The lefty can top 101 mph, has a good feel for his breaking ball and has developed a changeup that Matheny recently said might be his second-best pitch.

Fastball control will dictate where Brentz lands, but his ability to light up the radar gun -- especially as a lefty -- has turned heads this spring.

“You got a left-handed arm that can hit triple-digits,” Matheny said after Brentz first burst onto the scene. “We don’t need you to have deception, we don’t need you to hit corners. We need you to use the whole thing and let her go. I think he’s a potential weapon that could be a lot of fun to watch develop at the next level.”