PEORIA, Ariz. -- In one of the least surprising developments in Mariners camp, Luis Castillo was named the club’s Opening Day starter on Monday morning by manager Scott Servais. Yet, even with his standing as one of the best right-handers in the American League, Castillo himself said that he was surprised by the assignment.

Really? Why?

“I was a little shocked and super happy about it,” Castillo said through an interpreter one day later. “You guys might have known, but I didn't. I mean, we have such a talented rotation that it could go either way.”

Going further, Castillo called Seattle’s 2024 rotation -- which will also include George Kirby, Logan Gilbert, Bryce Miller and Bryan Woo -- the best that he’s ever been a part of.

“Apart from them being young and some of them have barely started their careers, I think that if they can stay healthy, we can be a very good team,” Castillo said.

In leading the charge for the March 28 opener at T-Mobile Park, Castillo will start opposite the Red Sox and up-and-coming righty Brayan Bello, who signed a six-year, $55 million extension earlier this month that signaled his long-term status within the organization.

This will be Castillo’s second straight season-opening start with Seattle after coming over at the 2022 Trade Deadline, and fourth of his career, dating back to his six seasons in Cincinnati.

“I'm already expecting all those good vibes and energy coming from the fans out in Seattle,” Castillo said.

Despite his pedigree, he was the obvious choice this spring, even within a loaded Mariners rotation -- the track record of his third career All-Star selection last season, a fifth-place finish in the American League Cy Young Award vote and his veteran standing within a young starting five above all.

Castillo said at this time last year that he had three explicit goals, and he accomplished the first two before a dip in September took him out of the race for the league’s top pitching award. He said Tuesday that the trifecta of ambition remains the same, as it has for the past seven years.

“I think it's shifting a little bit like it often does with players,” Servais said. “I think Luis is looking to establish himself as maybe the elite pitcher in our league, instead of one of the elite pitchers in our league. And we'll see. You need to stay healthy and continue to get better and make adjustments and do all the things he's capable of doing.”

How, and why, is Castillo raising his internal expectations?

“A lot of it has to do with how much I love this game,” Castillo said. “If I chose this profession, it was for a reason and I'm going to give it 110% every time I get a chance to get on the mound. So I think that's what's led me this far in this career, having that mentality that I just want to keep improving in this profession.”

Castillo is entering the second year of a five-year, $108 million extension, which he signed less than two months after his arrival in the blockbuster trade that represented one of the Mariners’ most monumental moments post-rebuild. Beyond the dollars, he said back then that the comfort within the clubhouse was a big reason behind his desire to stay with Seattle. And for a player who likes to socially swim in the proverbial shallow end, it’s only grown since.

“Apart from having a talented group, I think communication has been a big key within this group,” Castillo said. “And you communicate with him so much that you become kind of a family.”

In three career Opening Day starts, Castillo is 0-1 with a 5.40 ERA (nine earned runs in 15 innings), 14 strikeouts, five walks, one homer allowed and a 1.07 WHIP. He did not factor into the game’s decision last year, when he twirled six shutout innings and gave up just one hit in an eventual win over Cleveland.