Triston Casas of American Heritage High School in Florida was Boston’s first-round draft choice in 2018. This season at low Class A Greenville, he is batting .263 with six home runs and 32 RBI in 39 games. Associated Press/Michael Dwyer

Triston Casas pounded high school pitching last May, leading American Heritage of Plantation, Florida, deep into the state’s 6A playoffs.

Eleven months later, Casas was facing 96 mph fastballs and advanced curveballs. He was anything but dominant. The Boston Red Sox first-round draft pick in 2018 was swinging – and missing.

In his first April of professional baseball, Casas hit .208 with two home runs. In 77 at-bats with low Class A Greenville, he struck out 31 times.

“It’s been a really tough adjustment, to be honest,” Casas said recently by phone.

It is always a gamble to draft a high school slugger in the early rounds, let alone hand over $2.5 million in bonus money. But in Casas, a 6-foot-4, 240-pound left-handed power bat, Boston figured it had someone special.

And maybe they have.

This May, Casas, 19, is batting .333 (20 for 60), with a 1.041 OPS and four home runs. With only 11 strikeouts, his K-rate dropped from 40 percent in April to 18 percent in May. Overall, he is batting .263 with six homers and 32 RBI in 39 games.

“He’s made some nice adjustments as the season’s gone on and looks to be a formidable, power-hitting first baseman at this point,” said Greg Norton, the Red Sox minor league hitting coordinator. “Really works hard. Good attitude. Really good kid.”

Pushing a player to Class A, a year after high school, does not always work.

Last year, Boston promoted 2017 second-round draft pick Cole Brannen to Greenville. Brannen, then 19, batted .157 through mid-May and was demoted.

This year, Boston’s 2018 second-round pick Nick Decker, another high school slugger, is remaining in extended spring training until short-season Lowell begins play in June.

The Red Sox figured Casas was ready for Class A – even though he played only two games in the Gulf Coast League last summer before a thumb injury ended his season. He was someone who could handle the challenge.

“At a young age, I learned not to focus on results, but on the process,” Casas said, “whether be in baseball or anything.”

In baseball, Casas has turned it around.

“I knew this would be my biggest jump (from high school to pros). These pitchers are a big step up,” Casas said. “It was a struggle to find my timing and my swing.

“I started seeing the ball a little better; trying to relax, remembering what got me here. I cut down the strikeouts. That was a key for me – putting the barrel on the ball.”

Depending on Casas’ progress, a late-season promotion to advanced Class A Salem is a possibility.

JOSH OCKIMEY is still the biggest slugger in the Red Sox minor league system, with 11 home runs for Triple-A Pawtucket, including six in the past eight games. Ockimey, 23, who played in Portland last year, is batting .223.

But with 30 walks, he has an on-base percentage of .393. Add that to his .598 slugging average and his OPS is .991.

JARREN DURAN was featured in this space recently with speculation that the Salem outfielder could be in Portland by this summer. Maybe we should move up the timetable – end of May? – if Duran keeps raking. After recording a double and walk Monday night, Duran is batting .405, with a 1.121 OPS. He has 12 doubles, three triples, two home runs and 13 stolen bases in 39 games.

PITCHER KUTTER CRAWFORD may reach Hadlock Field before Duran. Crawford, 23, a 16th-round draft pick in 2017, out of Florida Gulf Coast University, is 3-2 with Salem, with a 2.72 ERA, and 52 strikeouts and 15 walks in 43 innings.

CHANDLER SHEPHERD was a pitching prospect on the rise when he recorded a 1.80 ERA in 22 relief appearances for the Sea Dogs in 2016, before a promotion to Triple-A. He never repeated that kind of performance in Pawtucket. Moved to a starter last season, he did have a 3.89 ERA, but was rocked this year in eight games (seven starts) with a 10.01 ERA.

Shepherd, 26, is now gone because Sandy Leon’s wife had a baby. Leon went on paternity leave last week and the Red Sox had to promote catcher Oscar Hernandez. To put Hernandez on the 40-man roster, Shepherd was designated for assignment. The Chicago Cubs grabbed him.