Pitching for the seventh-place 1902 Tigers, Siever led the AL with a 1.91 ERA but went 8-11. He had broken into the majors the year before, going 18-15 with 30 complete games in 33 starts. Sold to the Browns after the 1902 season, he went 13-14 and 10-15 with them before being let go. Reappearing with the Tigers in 1906, he helped them to their first pennant in 1907 with an 18-11, 2.16 record, but lost Game Three of the World Series 5-1.
