Jeff Samardzija says he doesn't have any excuses for a rare poor performance that he called "puzzling." The truth is, the San Francisco Giants' rotation is allowed to have a less than stellar effort every so often.

"The Shark" looks to bounce back and lead the Giants to their sixth victory in nine games on their road swing Saturday when the St. Louis Cardinals try to avoid their first four-game home losing streak in 11 months.

Samardzija has had a friendly competition with Madison Bumgarner and Johnny Cueto as they try to top each other during each turn in the rotation. He's certainly held his own with the two co-aces, matching Bumgarner in wins and trailing Cueto by two while all three own ERAs under three.

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After going 4-1 with a 1.41 ERA while pitching into the seventh inning in each of his first five May starts, Samardzija took a step back Monday when he allowed five runs over a season-low five innings in a 5-3 loss at Atlanta.

"Everything isn't always ideal. So you have to find a way to overcome it and play a little better," the right-hander explained to MLB's official website. "You can't make excuses in this game. Otherwise, there's too many to find."

Samardzija's subpar showing is one of only two outings that San Francisco starters have allowed more than three runs during a 26-game stretch in which they've posted a 1.73 ERA. Cueto allowed one unearned run over six innings in Friday's 5-1 win in the opener of this three-game series.

"I think every team will tell you that the pitching sets the tone, especially the starters,'' manager Bruce Bochy said.

Samardzija (7-3, 2.84 ERA) owns a 2.12 ERA in his last five starts against the Cardinals, though he hasn't faced them since 2014 while with the Cubs.

Matt Adams is 4 for 7 with two doubles and Yadier Molina is 10 for 20 off him, but Matt Holliday and Matt Carpenter are a combined 7 for 36 (.194).

Adams has gone 12 for 24 with three home runs and nine RBIs in his last eight home games, while Carpenter is 10 for 17 over his past four overall.

St. Louis (28-27) has averaged 7.8 runs and hit .294 in victories and totaled five runs and hit .190 in losses while splitting its last eight games. The club now hopes to avoid its longest home slide since June 30-July 3.

Right-hander Michael Wacha (2-6, 4.99) hasn't earned a victory since April 23, though he showed signs of improvement Sunday when he allowed three runs and four hits over six innings in a 10-2 loss at Washington.

Wacha had gone 0-3 with a 10.00 ERA over his previous four starts.

"He had the (three-run fourth inning)," manager Mike Matheny said. "After and before he was extremely good. I thought it was one of his best."

Wacha has been extremely good against the NL West-leading Giants (35-22), going 1-0 with an 0.47 ERA and 19 strikeouts in three meetings.

Brandon Crawford is 2 for 3 with a double off him, though Brandon Belt (1 for 6), Denard Span (1 for 7) and Gregor Blanco (1 for 8) have struggled.

Crawford went 2 for 3 with an RBI in the opener, leaving him 7 for 13 with four RBIs over his last four games at Busch Stadium.