During his career, Velasco has coached several national teams to podium finishes. He has won two Olympic medals (one gold and one silver), three World Championships (becoming the first – and so far only – coach to win both the men's and the women's titles), three European Championships, two Asian Championships, three Mediterranean Games medals (two gold and one silver), and a gold medal at the Pan American Games. He has also claimed eleven additional international titles.
Velasco became an assistant coach of the Argentina men's national volleyball team from 1981 to 1983. In 1983, he was invited to coach Tre Valli Jesi in Italy, where he remained until 1985. He then coached Panini Modena from 1985 to 1989, leading them to four consecutive Italian national championships from 1986 to 1989. In 1989, he was appointed head coach of the Italy men's national volleyball team, leading them to unprecedented success. His first trophy with the Italian side came at the 1989 Men's European Volleyball Championship in Sweden, where they topped their preliminary group with only one loss, advanced through the knockout stage, and defeated the host nation Sweden 3–1 in the final to win their first official international title.[3]
Velasco was a philosophy student and a Maoist militant during his university days, which led to his expulsion by the board of the National University of La Plata in 1974. After the 1976 Argentine coup d'état, he was forced to live in semi-clandestinity due to his previous political involvement — a situation that compelled him to move to Buenos Aires, where he secured his first volleyball coaching job.[9] He discussed coaching with football mastermind Pep Guardiola on multiple occasions. While Velasco was living in Italy, Guardiola once travelled hundreds of kilometres to meet the Argentine volleyball coach in person, simply because he had seen him in a television interview and wanted to learn from him.[10]