Marcus Elmore Baldwin (October 29, 1863 – November 10, 1929), nicknamed "Fido" and "Baldy", was an American professional baseball player who pitched seven seasons in Major League Baseball (MLB). In 346 career games, he pitched to a 154–165 win–loss record with 295 complete games. Baldwin set the single-season MLB wild pitches record with 83 that still stands today.

Born in Pittsburgh, Pennsylvania, Baldwin made his professional debut for a Cumberland, Maryland, team in 1883. Though signed by Chicago White Stockings president Albert Spalding to pitch against the St. Louis Browns in the 1886 World Series, Baldwin did not play after the Browns objected. He made his MLB debut for the White Stockings in 1887, when a writer for the Oshkosh Daily Northwestern called him the "swiftest pitcher in the National League" (NL). Released by Chicago player–manager Cap Anson, he signed with the Columbus Solons of the American Association (AA) in 1889, where he led the league in innings pitched (), losses (34), strikeouts (368), and walks (274).

In 1889, Baldwin, described as "intelligent and outspoken", recruited players for the Chicago Pirates of the Players' League (PL). Baldwin played for Chicago and finished the year as the PL leader in games played as a pitcher (58), innings pitched (492), wins (33), strikeouts (206), complete games (53), and walks (249), as the Pirates finished fourth in the league, ten games behind the first-place Boston Reds. A PL historian has described him as a star of the league. Back in the NL, he signed with the Pittsburgh Pirates, where he played from 1891 to 1893. Baldwin was arrested after the Homestead strike in 1892 and charged with aggravated riot, but never received a trial. He finished his MLB career with the New York Giants in 1893, and played several seasons for independent teams afterwards.

During his career, he batted and threw right-handed, weighed , and stood tall. After baseball, Baldwin became a physician and practiced at Passavant Hospital in Pittsburgh. He died of cardiorenal disease on November 10, 1929, and is interred at Allegheny Cemetery.

Early life Marcus Elmore Baldwin was born in Pittsburgh, Pennsylvania, on October 29, 1863, to Franklin E. and Margaret Baldwin. One of two children born to the couple, Mark and his family moved to Homestead, Pennsylvania in 1872. Franklin, a real estate speculator, previously worked as a steelworker and a nailer. As a child, Mark wanted to be a physician. Mark started to pitch for amateur Homestead teams in 1880, and, after high school, attended Pennsylvania State College (PSC), later renamed Pennsylvania State University.

Professional career Baldwin made his professional debut for a team in Cumberland, Maryland, in 1883, while he attended PSC. Two years later, he pitched for McKeesport, who finished first in the Western Pennsylvania League. According to an 1891 article in The Pittsburgh Press, he earned per game for pitching for McKeesport. According to another article in the Press, Baldwin had asked Pittsburgh Alleghenys secretary Scandrett for a tryout, and president William A. Nimick consented, but manager Horace Phillips opposed the idea and a tryout never happened. Instead, Scandrett wrote a letter recommending Baldwin to Duluth management. According to an article in the Pittsburgh Daily Post, McKeesport manager Frank Torreyson recommended him to Duluth of the Northwestern League in spring 1886 as a third baseman, but the Duluth Jayhawks played him as a pitcher as their pitching was weak.

On June 18, 1886, Baldwin struck out 18 batters, 12 successively, against the St. Paul Freezers. Baldwin had 19 strikeouts in 12 innings in a 4–3 loss at Oshkosh, Wisconsin on September 13, 1886. According to a friend of Baldwin, when Duluth fined Baldwin for poor play, he intentionally performed poorly until Duluth revoked the fine. According to a Pittsburgh Daily Post writer, Duluth won its league pennant due "chiefly on account of Baldwin's pitching". After a tryout, Chicago White Stockings president Albert Spalding signed Baldwin to a contract on October 20 to replace injured rookie Jocko Flynn: Chicago wanted Baldwin to play in the 1886 World Series (which ran from October 18 to 23), but the opposing St. Louis Browns objected, so Baldwin never played.

Chicago White Stockings (1887–88) Baldwin listed his birthdate when he played for Chicago in 1887 as 1867, which followed a theme of childishness and "extreme petulance" in him according to baseball historian David Nemec. In spring training prior to the 1887 season, a hotel employee found Baldwin and Tom Daly unconscious in their room, which smelled of gas. Either Daly or Baldwin accidentally blew out a flame in a gas light. Baldwin almost died, but both were revived. In preparation for the year, Baldwin joined Chicago during spring training in Hot Springs, Arkansas. Though in March 1887, Baldwin "expected to rank next to [John] Clarkson" among Chicago's pitchers, in April, The Sporting News reported Baldwin "[was] regarded in Chicago as little better than a failure". On May 2, Baldwin made his MLB debut against the Indianapolis Hoosiers in a 9–1 Chicago loss.

Later in the month, Baldwin held the Boston Beaneaters to one run in a 3–1 Chicago victory, part of a week in which Baldwin's development surprised a writer for The Post, who discounted the earlier evaluation of Baldwin as a failure. In June, a correspondent for The Clipper complimented Baldwin on his endurance and curveballs, while an Oshkosh Daily Northwestern writer called him the "swiftest pitcher in the National League". Baldwin finished the season with an 18–17 win–loss record, with 164 strikeouts and 122 walks over 334 innings pitched, as Chicago finished 71–50, third in the NL. By December, Baldwin had re-signed with the club.

With the sale of Clarkson to Boston, only White Stockings' player–manager Cap Anson, according to one prediction, believed the team could win a pennant. In a May 30 game against the Washington Nationals, Baldwin sprained a tendon in his right leg, an injury from which he did not return until early July. The White Stockings finished the season second in the NL, nine games behind the New York Giants, with a 77–58 record. Baldwin led his team with 15 losses and 99 walks.

Baldwin played on Spalding's 1888–89 World Tour. In a game seen by 12,000 spectators, Baldwin pitched for the Chicagos against the All-Americas in Melbourne as Chicago won 5–3, breaking a three-game losing streak. A monkey bit Baldwin on a ship on the tour after he fed it pretzels and beer; the bite has been reported in a different source as a serious scratch. On April 24, 1889, Anson released him and three other White Stockings and stated he would rather "take eighth place with [a team of gentlemen] than first with a gang of roughs"; according to Baldwin, Chicago did not restrict alcohol consumption on the tour (team owner Albert Spalding was a "temperance crusader"), and at various banquets Baldwin attended the wine "flowed freely". In addition to his alcohol consumption on the tour, Baldwin stated that after he hinted he would not sign for the salary of the previous season, he was released. Later in the year, Anson cited Baldwin's lack of pitch control as a reason for his release. Baldwin signed with the Columbus Solons of the AA on May 3.

Columbus Solons and Chicago Pirates (1889–90)

Baldwin, who debuted for the Solons on May 4 in a showing described by The Chicago Tribune as "anything but credible," explained his poor opening game as a result of unfamiliarity with AA coaching methods. By late June, a month in which he hit a double, three triples, and a home run over a three-game span, Baldwin was "doing better", according to a writer for The Chicago Tribune. According to a writer for The Saint Paul Globe, Baldwin pitched the "best ball in the [A]ssociation" in July. On August 31, Baldwin set the single-game AA record for strikeouts with 13 against the Browns. In his only season in the AA, Baldwin led the league in innings pitched (), losses (34), strikeouts (368), walks (274), and wild pitches (83), the last of which set a major league record that still stands today. Baldwin's 274 walks set a then-MLB record, while his strikeout total is the most post-1886 except for Nolan Ryan, Sandy Koufax, and Randy Johnson.

In November 1889, Baldwin met in Chicago with the National Brotherhood of Professional Baseball Players, a union of baseball players which would form the Players' League (PL) in 1890, where the union reportedly discussed the formation of a Chicago team. According to John Montgomery Ward, "the movement is an experiment on our part to have the men who do the work participate in the profits of the pastime". On why he joined the league, Baldwin said he was "not playing ball for principles", but rather for the "money that's in it", and on other players in the PL stated "not one of them ever had much faith in the principles which were said to have led to the revolt".

Despite an attempt by Anson to convince Baldwin to sign with an NL team in which Anson "spent more money than he [had] spent before", on November 21, Baldwin signed a PL contract for the Chicago team, nicknamed the Pirates. Baldwin's 1.77 "average earned runs per game by opponents" through May 21, 1890, ranked second-lowest in the PL, while his seven games played as a pitcher tied for second highest in the league.

Baldwin finished the year as the PL leader in games played as a pitcher (58), innings pitched (492), wins (33), strikeouts (206), complete games (53), and walks (249), as the Pirates finished fourth in the PL, ten games behind the first-place Boston Reds. PL historian Ed Koszarek has described him as a star of the league. When the PL disbanded on January 16, 1891, as the NL and AA ratified a new National Agreement, Columbus retained Baldwin under reserve, and Baldwin officially signed with the team in January 1891 for $2,900 (). After a discussion with Alleghenys team owner J. Palmer O'Neil in February, he jumped contract (thereby jumping leagues) and signed with Pittsburgh late that month or early in March despite saying he did not want to play for the club earlier in the year.

Pittsburgh Pirates and New York Giants (1891–93) In early March, Baldwin tried to convince Jack O'Connor of the Solons and Silver King of St. Louis to sign with Pittsburgh. Chris von der Ahe, owner of the St. Louis Brown Stockings, had Baldwin arrested for allegedly conspiring with O'Neil to sign players from St. Louis to Pittsburgh shortly thereafter. The charges were nolle prossed, and Baldwin later sued von der Ahe for false imprisonment. After years of litigation, Baldwin won a judgement of $2,525 () against the owner in 1897. Around early 1891, the Alleghenys nickname changed to the Pirates due to the club's habit of signing players from other teams.

In August he allowed only one hit against the Boston Beaneaters in a complete game. He ended an eleven-game winning streak of games in which he pitched in September. Baldwin had a 2.76 earned run average (ERA) and a 1.40 walks plus hits per inning pitched (WHIP) rate in his first year with the club as the Pirates finished last in the NL; Baldwin's 23 hit batsmen led the league, while his totals in innings pitched, wins, losses, and complete games led the club. He re-signed with the Pirates in November.