DETROIT -- Expect the Seattle Mariners to try to exploit a Detroit Tigers' bullpen that has struggled more often than not when they visit the Motor City for the opener of a four-game series on Monday.

Detroit's bullpen was ripped twice in four games in a series at Kansas City that ended Sunday with lefty Kyle Ryan surrendering a run in the 13th inning, giving the Royals a 2-1 win.

The Tigers relievers worked four scoreless frames before Ryan, who was just called up that day, gave up a bases-loaded single through a drawn-in infield.

Detroit called up Ryan and former closer candidate Bruce Rondon after sending out lefties Matt Boyd, who started Saturday, and reliever Blaine Hardy, after both got pounded during the weekend.

Ryan had been sent down because he had trouble getting left-handed batters out. Hardy got raked for five runs in an inning Friday and the only batter he faced Sunday doubled and scored.

Rondon was a bright spot in his first appearance in the majors after being sent home last September for poor work habits and attitude problems.

He worked two innings Sunday without allowing a runner and striking out three.

"He looked good," manager Brad Ausmus said. "He's got a little bit different delivery now. A little bit quicker leg kick; it seemed not only to be effective but it seemed like his fastball's getting on guys even more than it has in the past."

Mark Lowe has been a major disappointment all season. On Saturday, he gave up six straight hits after getting the first out of the eighth and had to be relieved by multi-position player Andrew Romine.

Rondon has eliminated his hip turn and is now both shorter and quicker to the plate without losing any of his triple-digit fastball. If he can pitch effective relief, it will enable Ausmus to use him in the sixth through ninth innings.

The bullpen sports an ERA close to 5.00 and its only reliable performers are closer Francisco Rodriguez and lefty Justin Wilson, who missed nearly a week with a tender elbow before turning in a scoreless inning Sunday.

"All the reports are his attitude's been real good," Ausmus said of Rondon. "He's been working hard, he's lost some weight while he's down in Toledo. Hopefully this is the Bruce Rondon everybody's been dreaming about."

Manager Scott Servais hopes Detroit will be a tonic for a Mariners' team that is second in the AL West at 36-33 but has lost seven of its last 10 and 15 of 23.

Seattle has lost starters Felix Rodriguez and Wade Miley to injury and Sunday right-hander Taijuan Walker was removed after five scoreless innings because of problems with his arch, which limited him to 3 1/3 innings in his previous start.

"I just felt it a little after the first at-bat and it didn't really get any better," Walker said. "It happened in the first inning and just kept getting worse."

"He really competed his tail off," Servais said. "He gutted it out that fourth and fifth inning. I would have liked to have kept riding him because he was getting them out, but the information I got, everybody felt it was best to get him out of there at that point."

Servais is worried the Mariners will have to plug another starter into its rotation in five days.

There was limited good news for Seattle. Hernandez no longer has inflammation in his calf and is out of his walking boot. He'll play some light catch after Seattle settles in Detroit.

"He's not having any issues," Servais said. "Normal everyday living is fine. We had to get it calmed down before we could do anything."

He's been out since June 1.

Miley played some light catch prior to Sunday's game in Boston with no immediate bad reaction in his right shoulder.

"I think he's going to be fine when he does come available to get back into the rotation," Servais said. "It's exactly what we figure it was, and we just needed to calm it down and give him two or three days off, skip a start or two and then get back after it."

The Mariners will send right-hander Nathan Karns (5-2, 4.06 ERA) out to face the Tigers' Mike Pelfrey (1-7, 4.79 ERA) in Monday's series opener.

Karns has 77 strikeouts in 71 innings and is familiar with Detroit. He started against the Tigers for Tampa Bay last year and relieved once, going 1-0 with a 2.00 ERA over the two games.

Pelfrey has faced the Mariners just twice in his 11-year career, going 0-1 with a 2.03 ERA in 13 1/3 innings against them.