He played in the American Association (AA) with the St. Louis Browns, and in the National League (NL) with the Boston Beaneaters and Cleveland Spiders.

"Happy Jack" (nicknamed due to his pleasant demeanor) was born to German immigrants and raised in Ashland, Pennsylvania.

During his seven seasons with the Beaneaters, he was part of four NL championships, and pitched alongside future Hall of Fame members John Clarkson and Kid Nichols.

In his last season in the major leagues, he played for the Spiders, widely considered to be one of the worst teams in MLB history.

[8][9][10] In June 1897, at the age of 19, Stivetts began his professional baseball career with the Ashland representative of the Central Pennsylvania League.

[11] It was there when an umpire named Tim Hurst noticed Stivetts' talent; who then recommended him to Charles Comiskey, the manager of the St. Louis Browns of the AA.

[19] The Browns opened the regular season on April 18 with a four-game series on the road versus the Louisville Colonels, and Stivetts started games two and four.

[24][25] On June 10, against Fred Smith and the Toledo Maumees, he hit two home runs in one game, the first of three times in his career he accomplished the feat.

[25][26][27][notes 1] In a game versus the Brooklyn Gladiators on July 6, manager Chris von der Ahe removed the Browns' starting pitcher Ramsey in the third inning and replaced him with Stivetts.

[35] When not pitching, or when he occasionally played in right field, the Browns used Joe Neale, Willie McGill, and future Hall of Fame executive Clark Griffith as part of the starting rotation.

[43] Though Stivetts initially denied it, it was reported on September 28, 1891 that he signed with the Boston Beaneaters of the National League (NL) for the 1892 season.

[44] Stivetts joined a pitching rotation that already included future Baseball Hall of Fame members John Clarkson and Kid Nichols, as well as veteran Harry Staley.

[45] With Boston's solid pitching staff, and their potent mix of position players consisting of future Hall of Fame members and established veterans, the team was expected to compete for a second consecutive NL championship.

[45][46] When analyzing the 12 National League teams, New York Giants captain, Buck Ewing, remarked about Boston's roster, "I think Clarkson has seen his better days.

[51][notes 2] With Stivetts now established, Clarkson became expendable and was released from the team on June 30, leaving Boston with a solid three-man pitching rotation for the remainder of the season.

The first game occurred on October 17; Stivetts started for Boston, and future Hall of Famer Cy Young pitched for Cleveland.

[2] On April 29, with the weather cold and rainy, he issued bases on balls to ten New York Giants batters, and surrendered 15 runs.

[64] His troubles adjusting to the new rules, and his athletic conditioning during June and July, prompted the team to sign Hank Gastraight for added pitching strength.

[1][66] With the previous season's inconsistencies behind him, Stivetts was re-signed and was the team's starting pitcher for Boston's season-opening game on April 19; a 13–2 victory versus the Bridegrooms of Brooklyn.

[69][70] Boston finished in third place among the 12 NL teams in 1894, and Stivetts won 26 games, though most of his numbers in important statistical categories failed to improve or became worse.

[1] In early November, due to the threat that a new American Association was near formation, the National League clubs were quick to sign their players without much negotiating.

[72] In March, shortly before the 1895 season began, Stivetts claimed he was in "excellent physical condition", and that he was "many pounds lighter than he was at this period last year".

[75] During the 1893 season, Stivetts involved himself in a dispute between two catholic players, Tommy Tucker and Hugh Duffy, and their manager Frank Selee.

Factions formed, with Duffy, Tucker, and Tommy McCarthy on one side; Herman Long, Bobby Lowe, and Stivetts on the other.

[76][77] His W–L record slid to 17–17, while his ERA improved slightly to 4.64 in 291 innings pitched, as Boston fell to fifth place, 16.5 games behind the NL champions from Baltimore.

[98] Created after the 1893 season by Pittsburgh Pirates owner William Chase Temple, the winner of the best-of-seven game series was awarded possession of a silver ornate cup, and 65% of the proceeds to be distributed to the players.

Due to the Beaneaters' solid, four-man starting pitching rotation of Nichols, Klobedanz, Lewis, and rookie Vic Willis, his role with the team was expected to be as an extra outfielder.

[105] In a game versus the Reds on June 9, the score was tied 5–5 in the bottom of the ninth inning when Stivetts connected for a pinch-hit, walk-off solo home run.

[120] Kid Nichols remarked in 1902 that Stivetts' speed was as fast as Rusie, and could have extended his career much longer had he taken better care of his body.

[121] Baseball writer O. P. Caylor wrote that Stivetts' issues were entirely his own, blaming his hard-drinking lifestyle and his inability to remain in good condition.