Seattle is still scrapping for a spot in the postseason while Oakland has been eliminated for a long time. Probable starter Castillo for the M’s has been on fire lately with a 4-0 record in his last 5 starts and a 1.60 ERA. Two of his last 5 starts had more than 6 innings of shutout ball. Probable starter Blackburn for the A’s has a 5.73 ERA and an abysmal 2.09 WHIP in his last 3 starts, where he has only averaged 3.7 innings pitched.
Castillo also has a superior bullpen to support him when he comes out after his 6 or so innings.
Head-to-head this season the Mariners hold a 9-1 edge in their last 10 against the A’s, where the average run differential in the Mariners’ wins is +4. Lay the runs on this one and take the Mariners.