KANSAS CITY, Mo. -- The past three years, the Kansas City Royals had the best and most feared bullpen in the majors.

If the Royals held the lead after six innings, the shutdown bullpen could be counted on to hold it the final three innings. It included Greg Holland, Wade Davis, Kelvin Herrera and Luke Hochevar.

But that bullpen is no longer. Holland had Tommy John surgery last September and hasn't thrown a pitch this year. Hochevar had surgery for Thoracic outlet syndrome. Davis has been on the disabled list twice this year with a forearm strain. Only Herrera has been healthy the entire season.

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"You're dealt a hand of cards. You play those cards," Royals manager Ned Yost said. "In the past, we had a really, really good idea what we were going to get coming out of the bullpen. Last year, we knew what we were going to get with Holly, with Wade, with Hoch, with Herrera.

"We're in a situation now through injuries, we're not the same bullpen we were last year. Jack's (Joakim Soria) had great outings and he's had bad outings. You get into a situation and you pretty much understand what you're going to get from Kelvin. Wade's been through some issues. You're hoping when he goes out, he's going to be good, but with everybody else you're not sure what you're going to get."

The Oakland Athletics bullpen has outperformed the Royals' bullpen in winning the first three games of this series. A's relievers John Axford, Liam Hendriks and Chris Smith held the Royals to one single over the final four innings in an 8-0 shutout Wednesday.

"Our bullpen is really a strength for us," A's manager Bob Melvin said.

The A's bullpen is 2-0 with a save while allowing Kansas City one run on a balk and five hits over 12 1/3 innings in the first three games of this series.

The A's started five rookies, including left-hander and winning pitcher Sean Manaea, for the second straight game against the defending World Series champion Royals.

"We seem to be getting an infusion of intensity with these younger guys," Melvin said. "These guys are hungry to make a name for themselves."

The A's will start rookie right-hander Daniel Mengden for the series finale Thursday, but he has had limited success in the majors this year. He is 0-4 with a 9.39 ERA and opponents hitting .328 off him in his past seven starts after going 1-3 with a 2.81 ERA in June and holding opposing batters to a .221 average. This will be his first time to face the Royals.

The Royals will counter with veteran right-hander Edinson Volquez, who has won his past three decisions over the A's, including an April 15 victory at Oakland.

Volquez is unbeaten in his past seven starts, but that is a deceiving statistic. He is 2-0 with a 5.45 ERA and five no-decisions in that stretch. In his previous start Saturday at Chicago, Volquez surrendered four runs on nine hits and two walks over five innings, but the Royals rallied to top the White Sox 6-5.