Last name is pronounced “KOSS-iss.”...Graduated in 2018 from American Heritage High School (Plantation, Fla.)...Ranked by Baseball America as the No. 25 prospect in the 2018 MLB Draft...Hobbies include cooking and fishing...Was a three-time Gold Medalist with USA Baseball prior to his pro career...Honored as the 2017 Richard W. “Dick” Case Award recipient by USA Baseball, presented annually to the program’s top player...Led the U-18 national team to its fourth consecutive world championship title in 2017, earning tournament MVP honors with three HR and 13 RBI, both leading the tournament field...Since high school, has trained at The System 8, which has campuses in Pembroke Pines and Davie, Fla....Other notable MLB players to train at The System 8 include Miguel Cabrera and Eduardo Escobar...His brother, Gavin, played baseball at South Carolina and Vanderbilt...Took part in the Red Sox Holiday Caravan in December 2023, visiting Beth Israel Deaconess Medical Center, Boston Children’s Hospital, The Jimmy Fund Clinic, Greater Boston Food Bank, West End House Boys & Girls Club and The BASE, a Roxbury-based community organization that utilizes sports in a way to engage youth in a positive, success-driven culture by providing athletic training, coaching, competition and academic support...Attended Red Sox Winter Weekend in January 2024, signing autographs, posing for pictures with fans and taking part in panel discussions...Attended Red Sox Fenway Fest in January 2025, signing autographs, posing for pictures with fans and taking part in a Netflix panel.
2024
Made his second Opening Day roster (also 2023) but was limited to 63 games due to injury...Missed 98 games from 4/21-8/16 with a left rib strain...Joined George Scott (1967-68) and George Metkovich (1944-45) as the only Red Sox to make multiple Opening Day starts at 1B prior to turning 25 years old...Became the third-fastest player in franchise history (by plate appearances) to reach 40 career HR...Became the sixth player in Red Sox history to hit 40 HR and record 100 RBI in their first 215 career games, joining Ted Williams, Walt Dropo, Tony Conigliaro, Carlton Fisk and Nomar Garciaparra...On 9/22 vs. MIN-G1, became the 27th player to hit three HR in a game for the Red Sox (36th instance)...It was only the eighth instance of a Red Sox player hitting three HR in a game prior to turning 25 years old.
2023
Made his first career Opening Day roster...Started 115 games at 1B and two as the DH...Led the Red Sox in walks (70), OBP (.367) OPS (.856) and ranked second in HR (24)...Ranked among the AL’s top 10 in OBP (seventh), SLG (10th, .490) and OPS (T-5th)...Finished third in AL Rookie of the Year voting...Ranked among qualified AL rookie leaders in OBP (third), SLG (fourth), OPS (second), HR (second), RBI (fourth, 65), runs (fourth, 66) and walks (second)...Led BOS in average HR distance (405 feet) (min. three HR)...Ranked in MLB’s 75th percentile or higher in xwOBA (92nd, .371), walk rate (93rd, 13.9), xSLG (89th, .500), barrel rate (86th, 13.1), chase rate (86th, 22.1), hard-hit rate (80th, 46.6) and average exit velocity (77th, 91.1)...Had a 1.034 OPS after the All-Star break...In 42 Interleague games, hit 12 HR with a 1.041 OPS (43-for-135, .319 AVG)...Became the first qualified Red Sox rookie to lead the team in OPS since Fred Lynn in 1975 (see table on previous page)...His .856 OPS was the highest by a qualified Boston rookie since Nomar Garciaparra (.875) in 1997...Became only the fourth rookie to lead the Sox in walks, joining Joe Foy (91 in 1966), Ted Williams (105 in 1939) and Marv Olson (61 in 1932) (source: Elias)...Became the ninth Red Sox player to reach 25 HR in 135 games or fewer but only the third to do so at the age of 23 or younger: Ted Williams (1939) and Tony Conigliaro (1964, ’65).
2022
Attended his second ML Spring Training camp as a non-roster invitee...Began the season with Worcester and hit three HR with seven RBI in his first seven games...In 33 games for the WooSox after being reinstated from the injured list on 7/26, batted .311 (38-for-122) with a .959 OPS, 11 2B, one 3B, five HR, and 16 RBI. During that span, walked 21 times with 28 SO...Reached base safely in 16 consecutive games for the WooSox from 8/16-9/2. Hit .356 with a .472 OBP during the season-long streak (21-for-59, 12 R, 6 XBH, 12 BB)...Selected to the active ML roster on 9/4 and made his debut that afternoon vs. TEX. Started at 1B and recorded his first MLB hit (single, fifth inning)...At 22 years and 232 days old, became the youngest Red Sox to play 1B in more than 50 years (Cecil Cooper in September 1971)...Hit his first HR on 9/6 at TB, a two-run shot in the second inning off JT Chargois. Prior to Casas, the most recent Red Sox to homer at 22 years of age or younger were Jonathan Araúz, Rafael Devers, and Andrew Benintendi...Hit a two-run HR to left field on 9/13 vs. NYY off Gerrit Cole, his first career HR at Fenway Park (see table on right). Also stole his lone base of the season...Went 3-for-38 (.079) in his first 14 games through 9/21, then 12-for-38 (.316) in his final 13 games...Hit three HR in a six-game span from 9/22-27. Hit a solo HR in the seventh inning on 9/22 at NYY, his first career game at Yankee Stadium...Reached via walk in three straight games from 9/22-24 at NYY (2 BB on 9/23 and 3 BB on 9/24)...Recorded a season-high three RBI on 9/24 at NYY. Hit a two-run HR in the second inning to give the Sox a 2-0 lead and worked a bases-loaded walk in the sixth inning...Recorded a .655 OBP during a seven-game stretch from 9/23-29, reaching base in 19 of 29 PA (9-for-19, 10 BB)...Reached safely in a season-best seven consecutive games from 9/26-10/2 (.517 OBP, 9-for-23, 6 BB)...Played three games for Licey in the Dominican Professional Baseball League following the season.
2021
Spent most of the season with Double-A Portland (77 G) and played nine games for Triple-A Worcester, his first experience at each level...Started 80 games at 1B and six at DH...Also played for Team USA in the WBSC Americas Olympic Baseball Qualifier and 2020 Tokyo Olympic Games, earning a spot on the All-Olympic Team after helping USA win a Silver Medal (see box on right)...Led Double-A Northeast in OBP (.395) and ranked among leaders in AVG (8th, .284), OPS (7th, .879), and BB (8th, 49)...Ranked among Red Sox minor leaguers in RBI (9th, 59), OBP (7th), OPS (5th), BB (3rd) and runs (10th, 63)...Named Double-A Northeast Player of the Week for 8/30-9/5 and to the MLB Pipeline Prospect Team of the Week for 5/10-16 and 8/30-9/5...Posted the Sea Dogs’ two longest on-base streaks of 2021...Reached safely in 27 consecutive games from 5/9-6/24 (.400 OBP, 30 H, 17 BB) and in 16 consecutive games from 8/27-9/19 (.507 OBP, 19 H, 18 BB)...Homered twice in three games, all with Portland (5/12 at Hartford, 9/3 at New Hampshire, 9/4 at New Hampshire)...Began the season with Portland and hit .328 with a .952 OPS in 17 games before joining Team USA for the WBSC Americas Olympic Baseball Qualifier...Went 4-for-6 with two HR, a double and a career-high 6 RBI on 5/12 at Hartford...Placed on the inactive list on 5/24 and joined Team USA in Florida...Helped the team qualify for the Tokyo Olympics, starting each game at 1B and going 6-for-15 (.400) with two 2B, two BB and three RBI...Reinstated on 6/7 and played in 30 games with Portland from 6/8-7/15...Homered in back-to-back games at Reading on 7/13 and 7/14...Placed on the inactive list on 7/16 to join Team USA in Tokyo...Played in all six games for Team USA and was named to the All-Olympic Team after leading all players in HR (3) and RBI (8)...Went 5-for-23 (.217) with three BB...Helped USA earn a Silver Medal with a 4-2 record...Reinstated from the inactive list on 8/10...In 30 games after returning from Team USA, spanning 8/11 through the end of the season, hit .304 with a 1.032 OPS (31-for.102, 23 R, 7 2B, 7 HR, 22 RBI, 26 BB, 22 SO)...Homered in three consecutive games from 9/3-4, totaling five HR and 11 RBI in 13 plate appearances...Promoted to Worcester on 9/22 and spent the rest of the season with the WooSox...In nine games, hit .242 with an .866 OPS (8-for-33, 6 R, 3 2B, 1 3B, 1 HR, 7 RBI, 8 BB, 8 SO)...Hit a two-run HR in his second plate appearance during his Triple-A debut on 9/22 vs. Rochester (3rd inning)...Following the season, was named an Arizona Fall League Rising Star with Scottsdale...In 21 games, hit .372 (29-for-78) with a .982 OPS, six 2B, one HR, and 11 RBI...In a poll of scouts conducted by The Athletic, ranked as the No. 2 prospect in the Arizona Fall League.
2020
Ranked by Baseball America as the Red Sox’ No. 1 prospect for the 2nd consecutive year...Was added to the Red Sox’ 60-man Club Player Pool on 8/20/20 and spent the remainder of the season at the Alternate Training Site.
2019
In 2019, named Red Sox Minor League Offensive Player of the Year...Also tabbed Minor League Player of the Year by the Boston Baseball Writers...Named a 2019 South Atlantic League mid-season and year-end All-Star in his 1st full season...Hit .256 (110- for-429) with 26 2B, 5 3B, 20 HR, 81 RBI, and 66 runs scored between Single-A Greenville and High-A Salem...In 2019, became the 1st Red Sox minor leaguer with 20+ HR in a season--all before turning 20 years old-- since Xander Bogaerts in 2012.
