1906 would open with Leifield on the big league roster. He appeared in 37 contests, finishing 24 of 31 rotation starts. He went 18-13 with a career and NL fifth best 1.87 ERA. He also ranked second in the league with eight shutouts and eighth with a 1.103 WHIP. He ranked second on the club with 111 strikeouts. At 93-60, the Pirates finished third in the NL, 23.5 games behind the 116-36 Chicago Cubs.
In 1907, Leifield racked up a career high an NL fifth best 20 wins, going 20-16 with a 2.33 ERA. He completed 24 of 33 starts out of a team leading and NL fifth most 40 overall appearances, including a league fourth best six shutouts. He ranked 10th in the league with a team leading 112 strikeouts. The Pirates finished second in the NL at 91-63, 17 games back of the repeat NL champion Cubs.
1908 would see Leifield continue to plug away, earning a 15-14 record with a 2.10 ERA. He completed 18 of his 26 starts, including an NL ninth ranking five shutouts. He also ranked seventh in the league by allowing 6.915 hits per nine innings. The Pirates made up ground on the Cubs, finishing only one game behind them at 98-56, still in second place.
Leifield went 19-8 (NL seventh in wins) for a league fifth best .704 winning percentage in 1909 with a 2.37 ERA. He tossed three shutouts, completing half of his 26 starts (of 34 total appearances). He ranked ninth in the league by walking only 2.41 batters per nine innings pitched. The Cubs were again great, at 104-49, but the Pirates were even better, winning the NL by 6.5 games at 110-42. It took the Pirates seven games to defeat the AL Champion Detroit Tigers. Leifield appeared in one contest, taking the loss in game four by surrendering all five Detroit runs on a walk and seven hits in only four innings of a 5-0 setback.
1910 would see Leifield post a 15-13 record for the Pirates, with a 2.64 ERA. He pitched two shutouts and completed 13 of his 30 starts, along with two saves out of his 10 relief appearances. Pittsburgh regressed to the mean with a 86-67 record, good for third place in the NL but 17.5 games out of the first place money (won by the Cubs, who else?).
In 1911, Leifield posted a .500 record for the first time in his career, at 16-16. He appeared in an NL ninth ranking 42 contests, starting an NL second best 37 and completing an NL fourth most 26 with two shutouts and a save. He ranked eighth in the league with a 2.63 ERA, seventh with 2.321 walks issued per nine, third with 318 innings pitched, and first, with 16 batters hit. Despite his pedestrian record, Leifield finished near the top of the league with a 5.6 WAR value. The Pirates were 85-69, 14.5 games behind the New York Giants.
After going 1-2 through six games in 1912, the Pirates dealt Leifield to the Cubs with CF/3b Tommy Leach for pitcher King Cole and utilityman Solly Hoffman. He ended up posting a 7-3 record with a 3.13 ERA over parts of the next two seasons with Chicago, retiring following the 1913 season.
In 1918, Leifield made a comeback with the St. Louis Browns, playing in parts of the next three seasons and compiling an 8-10 record and a 3.00 ERA. He retired for good following 1920. For a great read, check out his SABR profile, over at the SABR Bio Project.
All-Time Statline: Eight seasons, 109-84, 2.38 ERA, 239 games, 191 starts, 125 CG, 28 shutouts, seven saves, 1578 innings pitched, 1403 hits allowed, walked 481, struck out 546, 1.194 WHIP, 18.1 wins above replacement.