Arnold Mario Portocarrero
- Bats Right, Throws Right
- Height 6' 3", Weight 196 lb.
- School University of Missouri-Kansas City
- High School George Washington High School (Manhattan)
- Debut April 18, 1954
- Final Game June 15, 1960
- Born July 5, 1931 in New York, NY USA
- Died June 21, 1986 in Kansas City, KS USA
Portocarrero was signed as a free agent in 1949 by the Philadelphia Athletics and spent 1950 and 1951 in the minors. He was not in the minors in 1952 and 1953, spending time in the service during the Korean War.
In 1954 he made his major league debut in April, and as a rookie became the winningest pitcher for the Athletics who lost 103 games that year. Portocarrero won nine games while another rookie, Bob Trice, was second on the team in wins with seven. Portocarrero's ERA was lowest among the starters.
He continued to pitch for the A's when they moved to Kansas City in 1955 but spent most of 1956 in the minors with the Birmingham Barons, going 10-10 with an ERA of 3.47. He came back to the majors in 1957, going only 4-9 but posting an ERA of 3.92.
Traded to the Baltimore Orioles in April 1958, he had his best season, leading a below-.500 team with 15 victories. continued with the Orioles in 1959 and 1960 and then was in the minors in 1961 with the Rochester Red Wings.
- 15 Wins Seasons: 1 (1958)
- 200 Innings Pitched Seasons: 2 (1954 & 1958)