In 1912, Bader pitched in two games for the New York Giants. In his debut, on September 30, he pitched a complete game, 4–2 victory over the Philadelphia Phillies and their staff ace Grover Cleveland Alexander, foiling Alexander's bid for his 20th victory of the season. After that, Bader played for the Buffalominor league team, and went 16-7 In 1914, 20–18 in 1915, and in 1916 topped the league pitchers with a 23–8 mark.
Bader returned to the major leagues with the Boston Red Sox in 1917. He ended 2–0 with a 2.37 ERA in 15 games, all but one in relief. He enlisted in the Navy at the end of the season, but was discharged in June 1918 because of loose knee ligaments. He rejoined the Red Sox for the rest of the year and played his last game on July 18.