- Bats Right, Throws Right
- Height 5' 8", Weight 150 lb.
Mirabal was born in the USA and raised in Cuba. When his father died at a young age, his godfather Alex Pompez became his mentor. He shut out Pompez's Cuban Stars in both ends of a doubleheader when he was 16 years old, spending 1917-1919 with the Atlanta Black Crackers. He was 5-2 with a 3.66 ERA as a teenager for the Birmingham Black Barons in 1920, tying for the Negro Southern League lead in wins. He moved up to the Cuban Stars in 1921, going 0-1 with a 10.64 ERA against top eastern black teams. In 1922, he was 0-1 with a 21.60 ERA.
He established himself with the expansion Marianao club in the 1922-1923 CWL, posting a 4-1, 1.15 record (299 ERA+). He beat out major league star Dolf Luque for the ERA title by .38 and tied Luque for the lead with two shutouts. He helped the new Marianao team win the title its first year in the circuit. In 1923 in the Negro Leagues, he was 4-4 with a save and a 4.06 ERA (115 ERA+) for the Stars. He tied Wayne Carr and Isidro Fabré for 8th in the new Eastern Colored League in complete games (7).
The right-hander was superb for Habana in 1923-1924, going 7-2 with a 2.36 ERA (160 ERA+). He was third in ERA, behind Luque and Dave Brown, tied Luque and Jesse Petty for third in wins, was 5th with 41 K (between Petty and Oscar Levis), tied Fabré for the most games pitched (20), tied Lucas Boada for third with 12 starts, was 7th with 6 complete games, led with two shutouts and was second with 114 1/3 IP (7 2/3 behind Petty). His 3.5 Wins Above Replacement Player were third in the league, .1 behind Luque and Dobie Moore. In the Gran Premio season that followed the regular campaign, he was 1-1 with a save and a 1.35 ERA (226 ERA+) and would have won the ERA title had he qualified.
Mirabal was 4-8, but with a 4.24 ERA (127 ERA+) for the Stars in 1924. He tied Ping Gardner and George Britt for 5th in the ECL with 10 complete games but tied for second in losses (one behind Darltie Cooper) thanks to poor run support from the league's lightest offense. He was 2-3 for Habana in 1924-1925. He was 2-8 with a save and a 5.16 ERA for the Cuban Stars during 1925, but that was deceptive as his ERA+ was a still-decent 95. He tied for 4th in the ECL in losses, tied Cooper and Gardner for 9th with 8 complete games.
After not pitching in Cuba that winter, he had a 6-4, 3.97 record (109 ERA+) in 1926 in the Negro Leagues. He was one win shy of cracking the ECL top ten. He got into conflict with the Atlantic City Bacharach Giants' Chance Cummings that year, nearly hitting his head with three straight pitches; Cummings threw his bat at Mirabal, who fired it back at Cummings, leading to the Bacharach Giants charging the field and flinging their bats en masse at Mirabal without hitting him. After the game, apologies went all around. He was 2-1 in the 1926-1927 CWL and 0-1 in the Triangular season that followed the regular season. He did not pitch in the Negro Leagues in 1927. In 1928, he was 4-3 with a 2.77 ERA (181 ERA+) in his last regular action, a fine farewell note. James Riley reports that he had a no-hitter going into the 9th one game before allowing a hit with one out. He was third in the ECL in ERA, behind Jimmy Shields and Laymon Yokeley, led in WHIP (1.04, .15 ahead of Yokeley), was 9th with 5 complete games and was 7th in Wins Above Replacement (between Dick Lundy and Chaney White).
Following his playing days, he worked in the Stars' front office as Pompez's right-hand man. He was president of the Stars and later the New York Cubans.