MESA, Ariz. -- There has been a lot of buzz surrounding the Royals this spring, much of which comes from the $288.7 million contract extension for young star Bobby Witt Jr. and an aggressive offseason in which several pieces were added to the puzzle.

The starting rotation got a makeover with the acquisitions of veteran right-handers Michael Wacha and Seth Lugo, and Kansas City bolstered the lineup by signing slugger Hunter Renfroe. Some depth pieces like Adam Frazier were also added to the mix.

But one area that is perhaps underrated, both in terms of the attention it's gotten and what may come of it in 2024, is the bullpen. In Sunday afternoon’s 6-3 loss to the A’s at Hohokam Stadium, 5 2/3 scoreless innings from the Royals’ relief corps underscored that.

Right-hander James McArthur highlighted the effort with 1 1/3 strong innings that lowered his Cactus League ERA to 1.42 in five appearances. Add that to 16 1/3 scoreless frames last September/October, over which he struck out 19 and walked none, and you have the emergence of a formidable relief presence in both statistics and stature -- McArthur stands 6-foot-7 and weighs 230 pounds.

McArthur said it wasn’t one thing that just “clicked” for him beginning late last season. But he did pinpoint a particular pitch that has been a real weapon since then. It was an offering that he brought back into his arsenal upon being traded to the Royals from the Phillies, and that decision has paid major dividends.

“Right when I came over from the Phillies, they wanted me to start throwing the slider again,” McArthur said. “And I’m glad they did, because it’s helped me a lot and has kind of protected my curveball. … So them helping me with that, I think, was a big part of me turning it around at the end of the year.”

Manager Matt Quatraro was pleased with his relievers’ performance on Sunday, and with McArthur’s continued success, in particular.

“He kind of just picked up right where he left off last year,” Quatraro said. “The two breaking balls, a little bit of the cutter, the velo is up there in the mid-90s. He throws a ton of strikes. So, really positive. [The slider has been big], for sure. That was on the pitching department, identifying what he could use to help get lefties out, and he took it and ran with it.”

During a 106-loss campaign in 2023, Kansas City’s bullpen ranked 29th in baseball with a 5.23 ERA, below only the Rockies’ 5.41 mark. But with the emergence of the 27-year-old McArthur, as well as several key additions, the Royals could see marked improvement in that area this year.

Not only do the new relievers bring a wealth of experience, but also a standing that has made an impression with younger relievers.

Will Smith is the headliner of the moves the Royals made to bolster the ’pen. The 34-year-old left-hander owns a 3.67 ERA over 11 seasons and has won a World Series in each of the last three years -- he pitched for the Braves in 2021, the Astros in ’22 and the Rangers last season.

“I think we’re gonna be really good,” McArthur said. “When you add guys like Chris Stratton, Nick Anderson, and we’ve got John Schreiber now and Will Smith, guys that have been around for a while and have playoff experience, they just kind of have that aura around them when they walk around. You just want to be around them, you want to learn. You want to do things the way they do them.”

There seems to be a real sense that there’s been a vibe shift in the Royals’ clubhouse. Whether it’s the additions of veteran players and other acquisitions to shore up areas of weakness, or knowing that rising young stars like Witt and Vinnie Pasquantino are only becoming more mature in the game, hopes -- and goals -- are high.

That goes for the bullpen, too.

“I think there’s a big change in the culture and how we feel at the clubhouse,” McArthur said. “And the expectation for us in the bullpen and for the team is to win. I think we’ve got a lot of confidence going into it.”