In 1939, Rowe returned to the Tigers and, in 1940, he led the American League with an .842 winning percentage—a record of 16–3. His 16 wins, 3.46 ERA, and 138 Adjusted ERA+ (5th in AL) were instrumental in leading the Tigers to the 1940 pennant, and he finished No. 7 in that year's AL Most Valuable Player voting, though he fared badly in the 1940 World Series as he lost two games and had an ERA of 17.18. In Game 2, he gave up 5 runs in 3-1/3 innings, and was knocked out in the first inning of Game 6.