Nicknamed "The Pitching Professor" and "Parson", Lewis was an ordained minister who earned a master's degree from Williams College. He was one of three Welsh-born players to break into major league baseball in the U.S. He was 23 years old when he debuted with the Boston Beaneaters on 6 July 1896. Lewis pitched a full season in 1897 and earned 21 wins. He was one of three Boston pitchers to finish the season with more than 20 wins. Boston won the league pennant that season and repeated as champions in 1898. His 26–8 win-loss record in 1898 amounted to a league-high winning percentage. Lewis earned a 17–11 record in 1899, followed by a 13–12 record in 1900. He finished the 1901 season with a 16–17 record and a 3.53 earned run average. Lewis finished his career with a 94–64 record and a 3.53 ERA.
Academic career
After the 1901 season, Lewis retired from baseball to teach full-time at Columbia University. He was Instructor of Elocution at Columbia until 1904, when he returned to Williams College as a public speaking instructor and was later made an assistant professor. Lewis later left for Massachusetts Agricultural College, where he served as an English professor, department head and dean. He was the president of MAC between 1924 and 1927, and when his liberal philosophy created disagreements with the college's trustees, he submitted his resignation. Lewis became president of the University of New Hampshire in 1927. The university credits him with continuing the development of the school despite the difficulties associated with the Great Depression. He oversaw the construction of new buildings and athletic fields during his tenure. A recreational area known as Lewis Fields constructed from December 1933 to September 1936 was named in his honor. This area includes UNH's college football stadium—now known as Wildcat Stadium—which was known as Lewis Stadium or Lewis Field until it was formally named Cowell Stadium in 1952 in honor of former head coachButch Cowell. Lewis remained at UNH until his death in 1936. He is buried in Durham Cemetery in Durham, New Hampshire. Lewis was friends with poet Robert Frost, who contributed a reading at Lewis's memorial service.