The Jekyll-and-Hyde season for the Boston Red Sox continued over the weekend in Seattle, as Boston took two of three from the American League West-leading Mariners but dropped the finale when presented with a chance for a sweep.The Red Sox fell 3-1 to the Mariners on Sunday with Payton Tolle (three earned runs in six innings) on the mound but little on offense. That loss came after two strong offensive days from the club, with impressive starts from Ranger Suarez and Connelly Early. Suarez carried a no-hitter into the seventh Friday night in a 6-2 win.The Mariners offer a case study of what the Red Sox could have been. Despite playing in a weaker AL West, they still lead the division with an unspectacular 40-39 record. Meanwhile, the 31-44 Red Sox sit in the cellar of the AL East, six games back of the third wild-card spot.Both teams have top-10 pitching. Seattle has the league’s fifth-best ERA at 3.62, and the Red Sox have the eighth-best mark at 3.85. Offensively, they’re equally as awful, with Seattle owning a .232 average (25th) and .700 OPS (24th), while the Red Sox have a .243 average (18th) with a .692 OPS (27th).And yet, the Mariners have found a way to .500. Had the Red Sox played .500 ball to this point, they’d be sitting in third place in the AL East and squarely in the wild-card picture.Kiner-Falefa sidelinedAnother day, another injury for the Red Sox. Isiah Kiner-Falefa landed on the 10-day injured list Friday with left forearm inflammation. He told reporters he’d been dealing with the ailment for the past two weeks but that it flared up this past week — so much so that he didn’t take swings in batting practice because of the pain.