Tesreau initially signed with a minor league team of the St. Louis Browns in 1909. In, his contract was purchased by the New York Giants. After two years in the minors, Tesreau learned how to throw a spitball, which became his signature pitch. He started the second game of the season for the Giants. The New York Times wrote, "Tesreau has curves which bend like barrel hoops and speed like lightning. He's just the kind of a strong man McGraw has been looking for." In the 1912 World Series, Tesreau went 1-2 against Boston Red Sox ace Smoky Joe Wood. In, Tesreau was 17-7 and had a league leading ERA of 1.96. ERA officially became a statistic of Major League Baseball in, and Tesreau along with the American League's Walter Johnson became the first players recognized for leading the major leagues in that category. On September 6 of that season, Tesreau no-hit the Philadelphia Phillies 3-0. From 1912 to 1917, Tesreau remained a starting pitcher with the Giants. In 1918, he had an argument with manager John McGraw and quit the team in the middle of the season. In 1919, Tesreau refused to play for the Giants, and McGraw refused to trade or release him. Tesreau took a position as baseball coach for the Dartmouth Big Green baseball team of Dartmouth College, a position he held until his death on September 24, 1946. He won 348 games as coach for Dartmouth, often coaching against Joe Wood, who had become the Yale UniversityYale Bulldogs baseball coach. Standing, Tesreau was given the nickname "Jeff" because he resembled boxer Jim Jeffries. Tesreau held his opponents to a.224 batting average in his career, which was lower than Walter Johnson, Christy Mathewson and Pete Alexander even though each pitched considerably longer than Tesreau. He was also a better than average hitting pitcher, posting a.216 batting average with 40 runs, 2 home runs and 46 RBI. In six World Series games, he hit.300 with 2 RBI. Tesreau suffered a stroke while on a fishing trip in 1946. He died a few days later.
