Luis Castillo has established himself as one of the pre-eminent right-handers in the American League, carving his way through lineups with a mound presence that’s been described as unmatched. Meanwhile, at this time last year, Brayan Bello boasted all the potential of a long-term stalwart within a storied organization, yet he’s still looking to find his footing in the Majors.

The Red Sox recently showed their faith in Bello’s progression by signing him to a six-year, $55 million contract extension that includes a club option for a seventh season. And they showed it again by giving him the ball for Opening Day.

The 24-year-old Bello is trying to get to where the 31-year-old Castillo is. The matchup of these two pitchers from the Dominican Republic will be among the many intriguing storylines between the Red Sox and Mariners, who square off against each other at 7:10 p.m. PT on March 28 at T-Mobile Park for Opening Day.

Here’s a breakdown of the matchup:

RHP Brayan Bello
Previous Opening Day starts: None
2023 Season: 12-11, 4.24 ERA, 157 innings, 28 starts, 132 strikeouts

In late January, Bello said he was going right from the team’s Winter Weekend event in Springfield, Mass., to Fort Myers, Fla., so he could start his quest to become the Opening Day starter for the Red Sox. Mission accomplished. At a time the Sox are being transparent about building around their young core, Bello is right in the center of it.

“I do believe he's at a stage in his career and in the organization that he is the right one for that [first] game,” said Red Sox manager Alex Cora. “It's only [one game], but we made a big commitment with him a few weeks ago. He made a big commitment with us. It goes hand in hand. Last year, he proved that he belongs here. It just feels like he's done everything that we asked him to do throughout the offseason, in Spring Training. He keeps improving, and he'll be the guy in Game 1.”

Bello pitched like an ace for a good chunk of last season, and his overall numbers were brought down by some late-season fatigue. To rectify that, the righty went on a more rigorous offseason program. He also worked to refine his slider under the tutelage of Hall of Famer Pedro Martinez.

RHP Luis Castillo
Previous Opening Day starts: 2019, ‘21 with Reds and ‘23 with Mariners
2023 Season: 14-9, 3.34 ERA, 197 innings, 33 starts, 219 strikeouts

Castillo was the obvious choice this spring, even within a loaded Mariners rotation, thanks to his track record. Beyond his veteran pedigree within a young starting five, the righty earned his third career All-Star selection last season and placed fifth in the American League Cy Young Award vote.

In three career Opening Day starts, Castillo is 0-1 with a 5.40 ERA (nine earned runs in 15 innings), with 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.

“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,” Mariners manager Scott Servais said.