Barcello was born in the metropolitan area of Phoenix, Arizona, to Edward and Shelli Barcello, who were both former basketball players. Edward "led the state in scoring his senior year at Phoenix Brophy Prep in 1987, graduating with more than 1,000 career points and second only to future Duke star and NBA player Mark Alarie as the school's all-time leading scorers." Shelli "was the leading rebounder and second-leading scorer on Canyon del Oro's undefeated state championship girls team in 1986-87." Barcello started playing basketball when he was two. He grew up with his three sisters, Sarah, Amanda and Julia. Barcello attended high school on the varsity basketball team in all four years at Corona del Sol High School in Tempe, Arizona to win two state championship titles. As a freshman in 2013–14, he scored 15 points coming off the bench in the state championship game to help secure the school's third straight state title in overtime. In his sophomore season, he led the school to a 33–1 record and a second state title, and the Aztecs were ranked the consensus No. 3 team in the nation and when he was teammates with No. 1 2018 player Marvin Bagley III, who later transferred. Arizona coach Miller offered Barcello a scholarship after he poured in 51 points in a game as a sophomore against Gilbert Perry and Markus Howard. In his junior season, in the state tournament, Barcello surpassed 1,000 points in only his second varsity season. He led his team to the Division I tournament as the top seed. In his senior season, Barcello scored 2,254 career points at Corona shooting over 55 percent from the field and almost 90 percent from the charity stripe. He tallied 31 points in his team’s win over Christ the King in the Hoophall Classic. He also advanced to the finals of American Family Insurance National 3-Point Shooting Competition. He averaged 24.2 points, 3.0 assists and 5.8 rebounds per game.
Recruiting
Barcello was considered as one of the best players in the 2017 recruiting class by Scout.com, Rivals.com and ESPN. He was a consensus four-star prospect in the Class of 2017 and committed to play at Arizona over offers from Virginia, Butler, Indiana and Stanford.
College career
Arizona (2017–2019)
In his freshman year at Arizona, Barcello appeared in 21 games from his point guard position. He had a season high of 11 points in their victory over LBSU, which included three makes on four attempts from beyond the arc. He opened his collegiate career with a strong three-game run of 7.7 points, 3.3 rebounds and 3.7 assists per game while shooting 58.3 percent from the field and 57.1 percent from three-point range. Alex scored knocked down a pair of critical baseline jumpers in their run in its win at Oregon State. In his sophomore season at Arizona, he played in 30 of 32 games for the Wildcats. He registered three double-digit scoring games, opened the season with seven points and three rebounds in 15 minutes against Houston Baptist. He erupted for 16 points on 6 of 10 shooting in 13 minutes against Georgia Southern. He scored six points in six minutes at California. He scored seven points in 12 minutes at UCLA. He scored 12 points in 18 minutes at Utah. He notched his third double-digit scoring game of the season versus California, scoring 14 points in 18 minutes, going 7 of 7 from the free throw line. He earned an C.A.T.S. Academics Student-Athlete of the Month for February.
Barcello announced he planned to transfer from Arizona prior to the 2019–20 season. He opted to come to BYU where he received a waiver and played immediately instead of sitting out a season. Barcello scored 18 points in a 91–61 win over Weber State on December 21, 2019. He had 18 points and a career-high six three pointers, part of a BYU record 18 three pointers, in a 77–54 win over Loyola Marymount on February 14, 2020. In the regular season finale against Pepperdine, Barcello broke the left scaphoid bone in his wrist, which required surgery after the season was suspended. In his first season at BYU, Barcello averaged 9.3 points, 3.1 rebounds, 1.8 assists and 0.9 steals per game.
azcentral.com Big School Basketball Boys Athlete of the Year
Arizona Basketball Coaches Association Division I Player of the Year
2x 6A Central League state champions
2x East Valley Tribune Boys Basketball Player of the Year
All-East Valley Tribune Boys Basketball first team
MaxPreps.com High School Boys Basketball All-American honorable mention
FloHoops All-Peach Invitational First Team
FloHoops Peach Invitational MVP
;College
Personal life
He has three younger sisters that also play basketball named Sarah, Amanda and Julia. Sarah who is playing at Marist College in Poughkeepsie, New York had a successful freshman season appearing in 33 games and starting 19. Prior to Marist, Sarah and the Seton Catholic Prep captured the first 4A Conference girls basketball state championship title leading to a 29–4 record. Julia, "who is now playing at Colgate, left Seton two years ago with more than 1,458 points and another state championship, leading the school to a 32–3 record." "She holds the school's all-time rebounding and blocked shots records."
