After a slight delay in his return from the Dominican Republic, Marlins top prospect Sixto Sánchez is back in Jupiter, Fla., and eager to get underway. He’s also wearing the uniform number he’s long desired: the No. 45 worn by his childhood hero, Pedro Martínez.

“It means a lot,” said Sánchez on Monday of the number change. He wore the No. 73 that he was issued by the Marlins last spring throughout his dynamic rookie season, but he had his sights set on the No. 45 revered by many Dominican players. Sánchez, a native of San Cristobal, is also sporting a new tattoo on his right leg this spring, featuring the same No. 45 as the tattoo on his neck. “Since I was little, I used to watch Pedro pitch. I want to accomplish many of the things that he did.”

Sánchez, who has drawn comparisons to the Hall of Famer Martínez for years thanks to both his frame and his skillset, accomplished plenty in 2020. He put up a 3.46 ERA (129 ERA+) across his seven regular-season starts, including a 10-strikeout performance in his second career start against the Rays, before hurling five dominant, scoreless innings against the Cubs in Game 2 of the National League Wild Card Series and getting the ball again in Game 3 of the NL Division Series against the Braves.

Last summer certainly raised Sánchez’s profile back home, and he said the raucous welcome he got upon his return to the Dominican took him by surprise.

“I didn’t expect that many people to receive me the way that I did,” Sánchez said. “I even teared up a little bit. It was very special to be back in my neighborhood with my people.”

Marlins manager Don Mattingly had very little to nitpick about Sánchez’s first campaign, telling reporters that the hyped-up righty “came as advertised” with an electric upper-90s fastball and dastardly changeup. Perhaps his one blemish was how he fared in his final two regular-season outings against the Nationals and Braves -- two teams that were seeing Sánchez for a second time in the span of a few weeks -- in which he gave up a combined nine earned runs across seven innings.

One way to fix that issue? Encouraging Sánchez to stick to his considerable strengths, according to Mattingly.

“Last year it seemed like he played off one game to the next instead of just staying with how he wanted to attack guys,” Mattingly said of Sánchez. “If they jumped his fastball the first game, he might have gone with earlier offspeed the next time and not throw as many fastballs, instead of just attacking with the way he wanted to attack the guys.”

Sánchez’s postseason gem against the Cubs might hint at what Mattingly would like to see him do more. Facing a Chicago club that struggled mightily against elite velocity all season, Sánchez let his fastballs eat and went with them on 80 percent of his pitches, racking up six strikeouts and holding the North Siders to four hits.

Sánchez hasn’t yet thrown his first bullpen session after arriving to camp on Friday and going through the COVID-19 intake protocols, but he already knows the pitch he wants to attack and improve upon this spring: the high heater. Sánchez’s 97.6-mph average fastball velocity (combined four-seamers and sinkers) ranked third-best out of 160 starters that threw at least 500 fastballs last year, and hitters went 4-for-17 (.235) with seven strikeouts, per Statcast, when he placed those high-octane heaters in the upper-third of the strike zone and above. Sánchez recognizes that pitch could be extremely difficult for hitters to handle when it’s up toward their shoulders, and he wants to make it a more consistent weapon.

“It’s something that will help me to get better results,” Sánchez said. “Last year I tried to do it a lot, but this year, it’s my main focus to work on that pitch.”

Castano, Neidert will get ball first
Mattingly also announced his opening starter Monday -- for Spring Training that is. Second-year lefty Daniel Castano will take the ball for Miami’s spring opener against the Astros on Sunday at 1:05 p.m. ET at The Ballpark of the Palm Beaches, with fellow sophomore Nick Neidert taking the hill once Castano's outing is done.

• Marlins Spring Training schedule

It’s a chance for two young pitchers competing for the final spots in the Marlins’ rotation to make their opening statements. Castano acknowledged it’s an honor to start off the club’s very first game action of 2020, but he hardly needs much extra motivation. As a former 19th-round Draft pick and the self-described “last player” included in the 2017 trade that brought him, Sandy Alcantara and Magneuris Sierra over from the Cardinals, Castano has thrived in the underdog role.

“A lot of people didn’t know this, but [Cleveland Browns quarterback] Baker Mayfield was my first baseman in high school and we were hitting partners,” Castano said Monday. “He has that same M.O. of keeping all the press clippings and all that stuff. I’ve learned that I have to do the same thing. I pride myself on being a competitor, and I definitely do my best when my back is against the wall and people don’t think I can do something.”

Castano enjoyed a strong rookie summer after making his debut on Aug. 8 at Citi Field. The southpaw started in six of his seven appearances and saved his best for last, coming out of the bullpen to throw 6 1/3 shutout innings on Sept. 27 as part of a 5-0 win at Yankee Stadium. Castano called last summer and the Marlins’ surprising run to the postseason an experience that he’ll cherish forever, but he and the club have turned the page to 2021 -- beginning with his first start Sunday.

“The first thing when I saw [Mattingly], I congratulated him on his [NL Manager of the Year] Award, and the first thing he said was, ‘That was last year. This is this year,’” said Castano. “That really set the tone. Last year was awesome; it was a lot of fun making the playoffs. It was special and we were fired up, don’t get me wrong. But we want to show MLB that we can do something over 162 games, also, and that it wasn’t a fluke. We have a lot more up our sleeve.”

Spring Training tickets on sale Tuesday
The Marlins will make Spring Training tickets available to the general public beginning Tuesday at marlins.com/SpringTraining. The club’s first home game is against the division-rival Mets on Monday at 1:05 p.m. ET at Roger Dean Chevrolet Stadium. Seating will be reduced to 21 percent of typical capacity in accordance with health and safety protocols related to the ongoing COVID-19 pandemic, with groups seated at a minimum distance of six feet apart. Masks are required at all times, and nearly all transactions at the stadium will be cashless. Guests will be encouraged to use an app to order concessions to the comfort of their seats.