Born in
Sant Adrià de Besòs in the
Barcelona metropolitan area, Mir was scouted for
FC Barcelona when he was 12. He made his debut for the
B-team in the
Segunda División on 22 September 1974 in a 7–1 loss away to
Sevilla, totalling 17 appearances over the league season and being
sent off on 17 May in the penultimate game, lost 1–0 at
Recreativo de Huelva. In the
Copa del Generalísimo that season, he scored in a win over
La Liga club
Salamanca. On 23 November, profiting from
Carles Rexach's injury, he debuted in the first team in a 1–0 loss at
Real Betis, and in his next game two weeks later he scored in a 2–2 draw away to
Real Sociedad. He scored once more in his 12 games that season, also including a
UEFA Cup semi-final loss to
Liverpool at the
Camp Nou and an expulsion on 21 December in a 3–2 loss at
Valencia, alongside opponent
José Cerveró. Mir had been a protégé of Barcelona manager
Hennes Weisweiler, whose dispute with star player
Johan Cruyff ended in the restoration of
Rinus Michels as manager. The new Dutch manager did not include him in his plans. Nevertheless, he was transferred, with Barcelona retaining a buyback clause for 10 million
Spanish pesetas. In October 1978, Barcelona sold Mir to
Real Valladolid for 2.5 million, with the player choosing his destination ahead of an equal offer from
Elche. Manager
Helenio Herrera wanted to restore Mir in 1980 ahead of a
UEFA Cup Winners' Cup game against
Valencia, but was unable to as the player was registered with the reserves. He had a brief spell at
Sabadell the following season and was due to retire before his former Barcelona B manager
Luis Aloy convinced him to play one last season in the
Tercera División for
Sant Andreu. ==International career==