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4/16/2014 9:12 P.M. ET

Perez sent down as Affeldt returns to active roster

SAN FRANCISCO -- The impact of Jeremy Affeldt's return to the active roster might be felt more in left field than in the bullpen, which the left-hander rejoined Wednesday.

As anticipated, the Giants optioned reserve outfielder Juan Perez to Triple-A Fresno to clear roster room for Affeldt, who had been sidelined since late March with a sprained right knee. Not much was tangible about Perez's contributions, given his 0-for-8 performance in eight games. But he provided depth behind Gregor Blanco, the top outfield reserve who has replaced Michael Morse in left field almost daily.

With Perez gone and the bench thinned, Bochy acknowledged that Morse, who has been replaced by Blanco as early as the fifth inning, might stay in games longer.

Bochy said that if the Giants need an extra outfielder beyond Blanco, they could call upon some of their infielders. Brandon Hicks played some outfield in Spring Training and Ehire Adrianza is considered capable of diversifying himself. Joaquin Arias also has practiced in left field occasionally.

"When you have guys on the bench, you like them to be versatile," Bochy said.

Brandon Belt started 34 games in left field in 2011-12, but Bochy said he would remain at first base.

Bochy said Affeldt would be used in a variety of non-closing roles until he finds a niche. Eventually, Bochy would prefer to revert to a 12-man pitching staff if or when the starters begin working deeper into games.

Crawford sits out to protect tight hamstring

SAN FRANCISCO -- Brandon Crawford's right leg tightness prompted caution from Giants manager Bruce Bochy, who left the shortstop out of the lineup for Wednesday's game against the Los Angeles Dodgers.

Bochy observed that Crawford could have played if necessary. But Bochy didn't want to risk the possibility that discomfort would turn to injury.

"I'm concerned about [Crawford] pushing it and injuring his hamstring," Bochy said.

Crawford said he felt a tweak as he ran out a 10th-inning bunt single during the Giants' 3-2, 12-inning victory in Tuesday's series opener.

"Hopefully I'll be fine for [Thursday]," Crawford said.

Crawford went to the bench with a .318 batting average in 13 games. He also owned a seven-game hitting streak, during which he has built a .400 average (10-for-25).

Giants pitchers being stingy with free passes

SAN FRANCISCO -- The primary sources of the Giants' vastly improved control are as plain as the ink on a statistics sheet.

San Francisco's pitchers entered Wednesday with a National League-low 26 walks, or 1.9 per game. That average contrasted sharply with the rate of 3.2 they maintained last year, when they finished with 521 walks, the league's fourth-highest figure.

Starters Tim Hudson and Tim Lincecum are directly responsible for the turnaround. Hudson has established a franchise record by pitching 23 season-opening innings without issuing a walk. Lincecum, whose average of walks per nine innings ranged from 3.2 to 4.4 in the previous four seasons, has issued one free pass in 15 innings.

Nobody else has been scatter-armed, either. Right-hander Sergio Romo attributed the Giants' accuracy to following the game's basics.

"It's less an emphasis on not walking guys and more on making quality pitches," Romo said. "We're not crafty. What you see is what you get. We don't have time to beat around the bush."

The change in Lincecum reflects his increasing reliance on precision instead of power -- though, with 17 strikeouts, he still averages more than one per inning.

"He's not a thrower anymore," Romo said. "He's a guy who goes out there and pitches."

Chris Haft is a reporter for MLB.com. Read his blog, Haft-Baked Ideas, and follow him on Twitter at @sfgiantsbeat. This story was not subject to the approval of Major League Baseball or its clubs.