Bob Bowman, the man behind Michael Phelps’ legendary career, guided him to 28 Olympic medals. Phelps has credited his longtime coach for shaping the swimmer he became, once saying, “He’s taken me from a little boy and gotten me to where I am today.” But not every swimmer has found the same success under Bowman. An American record holder has chosen to walk away from the coach after a difficult stretch.
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Shaine Casas confirmed to SwimSwam on September 9 that he is no longer training with the University of Texas professional group led by Bowman. The decision comes less than two years before the 2028 Los Angeles Olympics and after a disappointing stretch for a swimmer who had recently established himself among the world’s best in the 200m IM, where Casas lowered his own American record in the short-course 200m IM to 1:49.43.
The move is all the more interesting because Casas had previously spoken highly of Bowman’s coaching. After Bowman took over the Texas program from Eddie Reese in 2024, Casas said the new training system “really complements the swimmer that I am and want to be.” Even after his breakthrough performance at the 2025 World Championships, he explained that Bowman had helped him deal with the pressure of racing alongside some of the best swimmers in the world.
“There’s no magic with Bob,” Casas said. “He instills in you competitiveness, determination, and the guts to own who you are.”
That’s why his departure from the group is even more notable. Casas first moved to Austin in 2022 after spending three years at Texas A&M. He had been just outside of the U.S. Olympic team for the 2021 Olympic Games and decided to enter the professional ranks and train with Texas legend Eddie Reese.
The new plan was quickly in effect. Casas was selected to the World Championships team for the 2022 season and claimed bronze in the 200m backstroke. He kept adding to his international medal count until finally he was a member of the first Olympic team in 2024. Reese was already retired, and Bowman was running the Texas program by this time. But still, Casas continued winning medals.
However, 2026 ushered in a different phase. At the Pan Pacific Championships, Casas had a bad showing and didn’t medal. His best individual result came in the 100 butterfly, where he finished fifth in 51.24. The bigger setback came in his signature event, the 200 IM. After winning silver at the 2025 World Championships, Casas finished 12th in 2:01.08 and failed to reach the final. Now, he has decided to make a change.
Casas is leaving Bowman’s professional training group, but he is not leaving Austin. He plans to continue training in the city for now, while keeping his next coaching arrangement private. “Time will tell,” Casas said about his future. “For now I’ll be in Austin training and focusing on what’s best for me as an athlete and a person.” Casas may be stepping away from Bowman’s training group, but the coach still has plenty to be proud of.
Marchand remains one of Bowman’s biggest success stories
One of the biggest success stories of his coaching career continues to be Léon Marchand, who has flourished under Bowman and remains one of the biggest names in swimming. At the 2021 Tokyo Olympics, Marchand finished 6th in the 400m Individual Medley, and he was soon making his mark as one of the world’s best swimmers.
After relocating from France to the United States following the Tokyo Olympics, Marchand started working with Bowman at Arizona State University. His ascendance in Bowman’s hands was spectacular.
His breakthrough came at the 2023 World Championships in Fukuoka, where he won the 400m individual medley with a time of 4:02.50, beating Michael Phelps’ previous world record of 4:03.84. Then, at the Paris 2024 Olympics, Marchand found even more success. He won four individual gold medals and became the first Frenchman to win four gold medals in one Olympic Games.
He also had a strong relationship with Bowman after the Olympics. In 2024, Bowman transferred from Arizona State to Texas, and Marchand followed him. Marchand started trainin in Austin with some of the best athletes in the world. The decision, however, paid off at the 2025 World Championships in Singapore. Marchand prevailed in the 200m individual medley and Casas settled for the silver and Hubert Kós for bronze.
All three were training at Bowman’s in Austin, which meant that the coach had one of the biggest events in the meet to himself. While Casas has now decided that a change is what he needs heading toward the 2028 Los Angeles Olympics, Marchand continues to train under Bowman, with their partnership still producing major success.