Baseball was Triston Casas’ first sport, which he took up in his early years. At the high school, he began his amateur career. He was able to score with a.414 average while playing for the University team for two years, totaling 11 runs and 53 RBIs in 53 games. In order to have a shot in the 2018 major league draft, he graduated a year early. In 2016 and 2017, he also participated in the Under Armour All-American Baseball Game, which elevated him to the position’s top prospect list.
He was selected in the first round by the Boston Red Sox in 2018. Casas was given a minor league assignment to the Gulf Coast League Red Sox. He sustained a ligament damage under his right thumb, ending his 2018 campaign. Casas joined Class A South Atlantic League at the start of 2019. He was later selected for their All-Star game. Baseball America awarded him the Offensive Player of the Year and Minor League Player of the Year for the Red Sox in 2019.