- Bats Right, Throws Right
- Height 5' 8½", Weight 162 lb.
- Debut September 18, 1915
- Final Game June 13, 1933
- Born April 3, 1896 in Philadelphia, PA USA
- Died September 21, 1965 in Philadelphia, PA USA
"The current performance of Harry Seibold . . . is one of the most amazing things in the National League struggle. . . A decade ago Seibold disappeared into the minor leagues and little more was heard of him until he appeared at the top of the International League list with Reading in 1928." - the Sarasota Herald, May 29, 1930
Harry "Socks" Seibold had two careers in the majors. In his first stint, he came up as a 19-year-old shorstop in 1915 and then pitched in 1916-17 and 1919 with the Philadelphia Athletics, while in his second stint a decade later, he pitched during 1929-33 for the Boston Braves. With the 1930 Boston Braves, he had the best ERA on the squad.
Seibold said he threw a curve ball, screw ball and knuckler. Source: The Neyer/James Guide to Pitchers.
He was a Philadelphia native who went 14-11 for Cedar Rapids in 1915 while hitting .263 and also playing shortstop. He came up to the 1915 Philadelphia Athletics in the middle of September 1915, playing shortstop but not appearing as a pitcher. The following season he continued as a two-way player, going 17-6 as a pitcher and hitting .233 in 91 games for Wheeling. He came up to the majors for five games, going 1-1 as a pitcher and appearing in one game in the outfield.
At age 21, he became a spot-starter for the A's, starting 15 of his 33 pitching appearances. His record was a not-very-impressive 4-16.
He did not appear in the majors in 1918. Spalding's Official Baseball Guide for 1919 indicates that he had been one of many major leaguers in the service.
Seibold spent much of 1919 pitching for one of the minor leagues' great teams, the 1919 Orioles. He went 10-5 on a team which went 100-49. He also spent a little time with the A's at the major league level, going 2-3 in 14 appearances.
Socks then dropped out of sight from the majors for a decade. In the minors, he pitched for teams such as Oakland, Seattle and Reading before coming back to the majors in 1929.
One source  believes that he was retired from pro ball during several years of the 1920's.
The Boston Braves were a terrible team when Seibold first pitched for them in 1929, but gradually improved until they were over .500 in his last year with them, 1933. Seibold never had a winning record with the team, although in 1930 his 4.12 ERA in a very high-scoring year was good enough for eighth-best in the league.
In 1934 he pitched one game for Albany.
In 1948 he managed the Seaford Eagles for part of the season.
The book Fair Dealing and Clean Playing: The Hilldale Club and the Development of Black Professional Baseball states that Seibold was one of a number of former major leaguers who played semi-pro ball in Philadelphia in the 1920's and 1930's.