Jarrod Parker is failing to get the same results he achieved earlier this year.

Parker began the season 5-3 with a 2.46 ERA, and he was holding opposing batters to a .209 average in his first 13 starts for the Oakland Athletics. But the rookie right-hander is now winless in three August starts, following a 5-0 road loss to the Kansas City Royals on Tuesday night.

In his past seven starts, Parker is 2-4 with a 6.15 ERA, and opponents are hitting .309 against him.

"It's just going to take a well-pitched game," A's manager Bob Melvin said to turn Parker around. "I thought he was on his way tonight, but one inning got him out of his rhythm and we had to take him out.

"Pitchers go through ups and downs. He's going through a tough part right now and he's just got to fight his way through it."

Parker held the Royals to two hits in the first four innings, but yielded five runs — four earned — three hits, two walks and two sacrifice flies in the fifth.

"I got behind and walked a couple of guys," Parker said. "It's inexcusable to put guys on like that. I started pitching backward. It's not my style. You minimize as much as you can and try to get back into the dugout. I didn't do the best job of it."

Instead, Parker didn't make it through the inning and was replaced by Jordan Norberto.

"The last couple of outings I've been leaving balls up," Parker said. "I've got to start pitching from my front side. It's a mechanical adjustment."

The A's offense did little against Jeremy Guthrie and two relievers. Oakland was shut out for a major league-leading 14th time. The A's failed to get a runner past second base.

Guthrie allowed only three singles in seven innings.

Guthrie, who struck out a season-high eight, ran his scoreless streak to 15 innings. He has yielded eight hits and struck out 14 in his past two starts, victories over the A's and the Chicago White Sox.

Guthrie (5-12) is 2-3 in five starts with the Royals, who acquired him in a July 20 trade with Colorado for left-hander Jonathan Sanchez.

Tim Collins and Greg Holland completed the shutout for Kansas City. Collins struck out all three batters he faced in the eighth inning, boosting his total to 77 — a Royals' strikeout record for a left-handed reliever.

Alex Gordon and Eric Hosmer delivered run-scoring singles in the Royals' five-run fifth inning that also featured sacrifice flies by Chris Getz and Billy Butler.

Kansas City also scored an unearned run after second baseman Jemile Weeks failed to handle Alcides Escobar's bouncer. That allowed Lorenzo Cain, who had walked, to score.

In the third inning, Josh Donaldson and Coco Crisp singled, but Donaldson was put out in a rundown between second and third. Right fielder Jeff Francoeur earned his 13th assist on the play, tying him for the major league lead among outfielders.

Notes: The A's placed 3B Brandon Inge on the 15-day disabled list with a sprained right shoulder. Inge joins eight teammates on the DL. The A's have used the DL 19 times this season. ... Oakland recalled INF Josh Donaldson from Triple-A Sacramento, where he was hitting .335 in 51 games. ... The Royals asked for unconditional release waivers on INF Yuniesky Betancourt, who was designated for assignment on Aug. 5 with a .228 batting average. ... Cain became the 13th Royals player to bat eighth. ... A's RHP Brandon McCarthy, Wednesday's pitcher, will make his second start since coming off the disabled list. McCarthy, who was out because of a shoulder strain, is 6-0 with a 2.25 ERA in his past eight starts. Rookie LHP Will Smith will start for the Royals.