The Mariners have been a thorn in the A's side all season, owning a 7-6 record against Oakland thanks largely to their pitching staff, which has allowed just 2.43 earned runs per game to their division rivals.
Felix Hernandez has faced the A's four times already and will get the start to open the series Friday night. He's 1-1 with a 3.10 ERA and 1.14 WHIP against Oakland, and has factored heavily into his team's ability to shut down the A's up-and-down offense.
Seattle enters the series holding Oakland to a minute .199/.256/.323 slash line on the season. To be fair, seven of the 13 contests between the clubs came in early April when the A's were a completely different team. For the first two months of the season, Oakland compiled a miserable 620 OPS. Since then, the club's OPS has been a far more respectable 756.
But after their low-water mark of the season on July 15, the Mariners are 30-18, just a half-game worse than the A's (30-17). They've quietly put together one of the better second halfs in baseball and they are primed to play the role of spoiler over the season's final month.
The A's are facing the loss of another veteran starting pitcher after Brandon McCarthy took a line drive off his head in the fourth inning of his start on Wednesday. That night, McCarthy underwent a two-hour surgical procedure that included the evacuation of an epidural hemorrhage and stabilization of a skull fracture.
A team release stated that McCarthy is resting in the critical care unit of the Alta Bates Summit Medical Center and there have been reports that the surgery should allow for a full recovery.
The A's have promoted righty Dan Straily from Triple-A Sacramento to join the starting rotation. He isn't currently slated to pitch until the team's next series in Anaheim.
Oakland's latest series against the Angels was a sobering one. The A's were coming off a nine-game winning streak only to be swept on thier home field by the team that's now just 2.5 games behind the A's in the standings.
The A's offense was outstanding during the streak, averaging eight runs per game. But in the three-game sweep to the Angels, the A's scored just five times. Now the A's are tied with both the Orioles and Yankees atop the Wild Card standings, with Tampa Bay just 1.5 games off the pace.
So which A's team will show up in Seattle? Will it be the team that hit 20 home runs during the winning streak, or the club that averaged just over a run per game to the Angels?
A.J. Griffin (4-0, 2.26 ERA) will look to right the ship against Hernandez (13-6, 2.51 ERA), who figures to remain in the Cy Young conversation until the season's end. Griffin threw well in his first start since returning from a shoulder flare up that cost him just under a month of the regular season. He allowed just a run on three hits in seven innings on the way to a 7-1 win.
Griffin's role on the team – as with each starting pitcher – becomes incredibly important in the stretch run. The A's are 20-48 when allowing four runs or more this year, which puts plenty of pressure on a pitching staff that's sending out four rookies and a veteran returning from Tommy John surgery. The offense has been hot in stretches, but the team's identity is its pitching staff.
Hernandez was good for most of his last outing against the Angels, but he allowed three runs in the seventh before being chased from the game with his team behind, 3-2. Hernandez threw three complete games in his previous five starts, including a perfect game against the Rays. Over that span, he went 4-1 with a 1.08 ERA and .137 average against.
The A's are hoping the innings are starting to wear on the talented right-hander and he loses some of his steam as his season winds down. But Hernandez' competitive nature would indicate his season is far from over and he would love to add to his impressive career against the A's.
Saturday night's game two will see Hisashi Iwakuma (6-3, 3.14 ERA) take on Brett Anderson (3-0, 0.90 ERA). Iwakuma, the 31-year-old rookie right-hander from Japan, didn't begin starting games for the Mariners until July 2. Since joining the rotation, he has been outstanding.
The Mariners are 7-4 in his starts, and he's allowed a 2.42 ERA and 650 opponents' OPS. His fastball is average (90 miles per hour) and he is very reliant on a split-finger fastball that he throws nearly 23 percent of the time. He also throws a very good slider and a "show-me" curveball.
In his last five outings, Iwakuma has allowed just 22 hits in 33 innings, yielding a 1.09 ERA with just nine walks.
In his three starts since returning from the big leagues after more than a year, Anderson has been lights-out. He's allowed just two earned runs in 20 innings, resembling the pitcher the A's hope can become a consistent force atop the rotation down the road.
Anderson has been a key addition to a rotation that has needed all the veteran leadership it can get. As the lone arm with more a year of major league experience, Anderson will be relied upon heavily down the stretch to be a stopper against some of the vaunting lineups the A's will see over the next few weeks.
Vargas will be making his fifth start against the A's this year. So far, he's gone 2-0 with a 1.98 ERA against Oakland, having allowed hitters a .185 average and just a .242 on-base clip.
Coco Crisp is one of the few A's players to have any semblance of success against the southpaw. Crisp is 9-for-27 against him in his career, while Yoenis Cespedes' only two hits against Vargas have been home runs, including the mammoth home run he hit in the Coliseum back in April.
Milone's noteworthy home-and-road splits have evened out somewhat as the season has gone on, but the disparity is still there. His home ERA sits at 2.77 with his road mark up at 5.30. But he's thrown well in his two starts at Safeco Field, allowing just four earned runs in 11 innings, with a 5-to-1 strikeout-to-walk ratio.
The lefty has had some issues getting right-handed slugger Jesus Montero out early in his career. Montero is 4-for-6 against Milone with a homer, double and three driven in.