Forsythe and Tim Beckham knocked Lobstein out of the game with solo homers in the sixth. J.P. Arencibia and Mahtook added solo shots in the seventh.
The loss halted Detroit's winning streak at two. The Tigers haven't won three consecutive games since Aug. 18-20, their only three-game winning streak since the All-Star break. They haven't swept a three-game series since the opening week of the season.