Villas-Boas went on to immense success with Porto, leading them to an undefeated season in the Primeira Liga—only the second time this had ever been achieved—and winning the title by more than 20 points, having conceded only 13 goals all season. Villas-Boas went on to follow up this success by leading Porto to win both the Portuguese Cup and the UEFA Europa League, thus completing a treble in his first season in charge. By doing so, Villas-Boas became the third-youngest coach ever to win the Primeira Liga (behind Mihály Siska in 1939 and Juca in 1962) and the youngest manager ever to win a European competition, at the age of 33 years and 213 days.
DDA is right about "achievements prior to their appointments, thus why life after Chels or United would probably take different courses."