Five years after they played together in a showcase of the best high school baseball players in America, Arizona Diamondbacks outfielder Corbin Carroll and Baltimore Orioles shortstop Gunnar Henderson won the Rookie of the Year Award on Monday, only the fifth time both leagues’ winners have been unanimous.

Because both started the season in the major leagues and were ranked among the top 100 prospects in baseball, their teams will receive an additional first-round pick in 2024 as part of the Prospect Promotion Incentive that the players’ union pushed for in collective-bargaining negotiations to discourage service-time manipulation.

Carroll, 23, is expected to finish high in National League Most Valuable Player voting that will be revealed Thursday after he hit .285/.362/.506 with 25 home runs and 54 stolen bases, the second most in the major leagues behind NL MVP favorite Ronald Acuna Jr.

The 22-year-old Henderson, who helped lead the Orioles to a 101-61 season and American League East title, rode a combination of power and smooth defense to the award and became the Orioles’ first Rookie of the Year since Gregg Olson in 1989.

Cleveland Guardians right-hander Tanner Bibee finished second — and, in doing so, received a full year of service time despite debuting in late April — and Boston Red Sox first baseman Triston Casas was third. New York Mets right-hander Kodai Senga took second in the NL, with Los Angeles Dodgers James Outman locking down third.

The last time both Rookies of the Year took 30 of 30 first-place votes was 2017, when New York Yankees outfielder Aaron Judge and Dodgers first baseman Cody Bellinger won the awards. The other seasons with two unanimous winners were 1997 (Boston’s Nomar Garciaparra and Philadelphia’s Scott Rolen), 1993 (California’s Tim Salmon and Los Angeles’ Mike Piazza) and 1987 (Oakland’s Mark McGwire and San Diego’s Benito Santiago).

Carroll led off and Henderson hit sixth in the Under Armour All-American Game, played July 20, 2018, at Wrigley Field, on a team that also included Kansas City Royals shortstop Bobby Witt Jr. and Yankees shortstop Anthony Volpe. Carroll went 2 for 3 with a run scored, and Henderson was 1 for 3 with a pair of RBIs.

“So many of the young, exciting players in our league happened to be from that year,” Carroll said. “I’m fans of them as well.”

With 6.0 FanGraphs wins above replacement, Carroll turned in one of the 10 most productive rookie seasons in the last half-century — no surprise to Arizona, which locked Carroll up to an eight-year, $111 million contract in spring training after he had excelled in 115 plate appearances during his debut late in the 2022 season.

The Diamondbacks snuck into the NL playoffs with 84 wins this year and ousted Milwaukee, Los Angeles and Philadelphia on the way to the World Series, where they lost to the Texas Rangers in their first appearance in more than two decades.

Carroll, a first-round draft pick in 2019, took pride in adding another pick — and the corresponding bonus-pool money of around $2.5 million — to the Diamondbacks’ coffers with the award.

“That’s probably what brought the most weight to chasing something like this for me,” he said. “Not for the personal fame or attention but that ability to benefit my team. I’m hoping to be here long enough where that draft pick is hopefully a star player on the Diamondbacks alongside me. Just being able to reward the front office’s belief in me in this way is really special.”

The last unanimous winner in the NL was Bellinger, and Carroll is the 14th since Rookie of the Year became an official award in 1949.

Senga, 30, thrived in his first MLB season after 11 years with the Fukuoka Softbank Hawks in Nippon Professional Baseball. With his baffling Ghost Fork, a split-fingered fastball that disappears from the strike zone as it approaches the plate, Senga was one of the few bright spots for a Mets team that faltered.

The 26-year-old Outman is the latest Dodgers development success story, holding down center field and hitting .248/.353/.437 with 23 home runs, 70 RBIs and 16 stolen bases.

Henderson debuted toward the end of the 2022 season, falling just 14 at-bats shy of exhausting his rookie eligibility. He had rocketed through Baltimore’s system after signing for $2.3 million as a second-round pick out of high school in Selma, Alabama.

After spending most of the first half of the season as Baltimore’s third baseman, Henderson shifted to shortstop — his natural position — and paired with Orioles catcher Adley Rutschman to form perhaps the best young duo in baseball.

A wrist injury hindered Henderson over the first month, but he healed and illustrated why he entered the year, like Carroll, as the betting favorite for the award.

“It all worked out,” Henderson said.

Among shortstops, only Corey Seager and Francisco Lindor — both of whom have contracts of $325 million or greater — hit more home runs than Henderson’s 28. Henderson also drove in 82 runs and scored 100.

“We got a taste of it being in the [ALDS],” Henderson said. “Just to hear the crowd’s energy for that, I’d love to experience that, especially at Camden Yards.”

Henderson was the 13th unanimous selection in AL history and the first since Seattle’s Kyle Lewis in 2020.

The 24-year-old Bibee, who joined the Guardians in late April, finished the season 10-4 with a 2.98 ERA — the fourth lowest in the AL among starters with at least 140 innings. A fifth-round pick in the 2021 draft, Bibee joined right-hander Gavin Williams and left-hander Logan Allen as one of the best trios of rookie starting pitchers on one team in baseball history. Bibee received 20 second-place votes and appeared on 27 of 30 ballots.

Casas, 23, beat a crowded field for third place. His 24 home runs ranked second behind Henderson among AL rookies, and his .367 on-base percentage was behind three Minnesota Twins: Edouard Julien, Royce Lewis and Matt Wallner. Casas beat out Rangers third baseman Josh Jung for third place.

Henderson and Carroll will receive $750,000 for winning the award as part of the pre-arbitration bonus pool in the CBA. Bibee will get $500,000 for his second-place finish, while Senga will not receive a bonus because he was previously a professional in Japan.

Others who received votes in the AL included Houston Astros catcher Yainer Diaz, Boston outfielder Masataka Yoshida, Julien and Volpe, who won the Gold Glove last week.

Others receiving votes in the NL: Colorado outfielder Nolan Jones, who was just three points behind Outman and had the most third-place votes with 11; Cincinnati‘s Matt McLain and Spencer Steer; and Miami‘s Eury Perez, Cincinnati’s Elly De La Cruz and San Francisco‘s Patrick Bailey, each of whom received one third-place vote.