Jonathan Schoop, Jake Rogers and Robbie Grossman homered and the host Detroit Tigers downed the Seattle Mariners 8-3 on Thursday.Grossman drove in three runs, while Rogers had two hits and two RBIs. Schoop supplied three hits as the Tigers collected two victories in the three-game series. Willi Castro added a run scored and an RBI.Tigers starter Tyler Alexander gave up one run on three hits in 2 2/3 innings. Joe Jimenez (1-0) pitched a scoreless seventh inning and was credited with the victory.Mitch Haniger hit a pair of solo homers for Seattle. Starter Justus Sheffield (5-5) gave up five runs (three earned) on six hits in four innings. The Mariners were charged with three errors as they finished 1-5 in the season series with the Tigers.Haniger, the second batter of the game, staked the Mariners to an early lead against Alexander with a 412-foot blast to left.Detroit took a 2-1 lead in the bottom of the inning. Schoop ripped a one-out homer, his team-high 10th of the season. Miguel Cabrera followed with a double and scored on Isaac Paredes’ two-out single.Rogers made it 3-1 with his homer to left field in the second inning. It was his third of the season and second in back-to-back games as he also homered in Detroit’s 9-6, 11-inning loss to Seattle on Wednesday.The Mariners scored a run in the fourth when Jake Fraley singled, stole second, advanced on a flyout and scored on Jake Bauers’ groundout.