SEATTLE -- Getting Wade Miley back from the disabled list might not be the ticket to the Seattle Mariners getting back into the pennant race, but it's a step in the right direction for a rotation that's had a rough June.

The veteran left-hander is scheduled to be back on the mound when the Mariners host Pittsburgh on Wednesday night, the final game of a two-game series with the Pirates (37-41).

Miley (6-3) was eligible to come off the disabled list Tuesday night and is listed as the Mariners' probable starter for Wednesday's game. Shoulder soreness landed him on the DL, costing the Mariners one of their veteran starters during a month when three of them -- Miley, Felix Hernandez and Taijuan Walker -- missed starts because of injury.

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Miley and Walker are expected back in the rotation this week, while Hernandez threw 15 pitches off a mound Tuesday and looks on track to be back in the rotation by early- to mid-July. Getting all the arms back, combined with the successful start of newcomer Wade LeBlanc last week, left the Mariners (39-38) with a tough decision to make -- and manager Scott Servais did just that when he announced veteran starter Nathan Karns would work out of the bullpen.

"Our club certainly welcomes the arm down there," Servais told reporters before Tuesday's game. "But more importantly, get him a breather, get him back on track."

Pittsburgh's rotation has had its share of issues as well this season, and the Pirates are hoping that touted prospect Jameson Taillon can help provide some stability. The 24-year-old right-hander is scheduled to make his fifth career start Wednesday night, having struggled his last two times out.

With veterans Gerrit Cole and Ryan Vogelsong ailing, and the rest of the rotation falling on hard times, the Pirates look to Taillon and fellow rookie Chad Kuhl to make an immediate impact. Kuhl's next start -- his MLB debut came over the weekend -- is scheduled to come Saturday at Oakland.

The Pirates could use a shot of youth in a rotation that has been struggling as of late. Jonathon Niese was the latest starter to have an off night as he allowed nine hits and five runs (four earned) over 4 2/3 innings in Tuesday night's 5-2 loss at Seattle.

"In the fifth inning," Niese said, "it just unraveled."

That phrase also applies to both teams' seasons because in large part to starting pitching. Neither rotation is hitting on all cylinders right now.

The Mariners are hoping that some healthy arms might get them back on track. Getting Hernandez back on the mound is of particular importance, so his brief bullpen session was a step toward resolving that issue.

"His arm looks great," Servais said. "Obviously, it's fresh."