1898 would see Willis make his major league debut with the Boston Beaneaters. He pitched eight seasons with the club, going 151-147 with a 2.82 ERA. This includes several season leading NL totals, including five shutouts and a 2.50 ERA in 1899, six shutouts in 1901, 51 games, 45 complete games, 410 innings pitched, and 225 strikeouts in 1902, 25 losses and 29 complete games in 1904, and 29 losses in 1905 (his ERA was only 3.21 at the time). After the 1905 season, the Beaneaters sent him off to the Pirates for utility infielder Dave Brain, first baseman Del Howard, and pitcher Vive Lindaman.
1906 would see Pittsburgh post a 93-60 record, good for third in the National League. Willis led a (mostly) four man rotation who totaled a 78-43 cumulative record, leading them at 23-13 (NL third in wins) with a team and NL fourth best 1.73 ERA. He was also third in the league with 322 innings pitched and with six shutouts. He got through the season having allowed exactly zero home runs, impressive even in the era of smallball.
In 1907, Willis again led the pitching staff in victories, at 21-11 with a 2.34 ERA. He tossed six shutouts, completing 27 of his 37 starts. He ranked seventh in the NL with a 1.035 WHIP and with a .656 winning percentage. The Pirates finished 17 games behind the pennant winning Chicago Cubs, with a 91-63 record.
Willis continued his domination of opposing batters in 1908, collecting a 23-11 (fourth in wins) record with a team second best 2.07 ERA. He completed 25 of his 38 starts, including seven shutouts. His 1.011 WHIP (NL fourth) was a career best, as was his 7.1 hits allowed per nine innings pitched. The Pirates missed out on the postseason by only one game, at 98-56 and just short of the Cubs for the pennant.
1909 would see Willis again post excellent numbers, going 22-11 (NL fourth in wins) with a 2.24 ERA. At one time during the season he won 11 in a row. The Pirates beat everyone on their way to a 110-42 record, facing the AL Champion Detroit Tigers in the World Series. Willis appeared in two games that series, losing game six and going 0-1 with a 4.63 ERA, allowing eight walks and 10 hits in only 11.2 innings.
Willis joined the St. Louis Cardinals for his final season in 1910, going 9-12 with a 3.35 ERA. He retired having appeared in the league’s top 10 in innings pitched in 10 out of his 13 seasons, including all four years in Pittsburgh. As a Pirate, he never finished worse than 10 games over .500. He was elected to the Hall of Fame by the Veteran’s committee in 1995. For a longer writeup, check out the SABR bio by Dan Levitt.
All-Time Statline: Four seasons, 89-46, 2.08 ERA, 160 games, 146 starts, 108 CG, 23 shutouts, three saves, 1209.0 innings pitched, 1011 hits allowed, walked 297, struck out 423, 1.082 WHIP, 18.5 wins above replacement.