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3/25/2014 8:24 P.M. ET

Bumgarner shrugs off allowing three Brewers homers

PHOENIX -- Madison Bumgarner's initial reaction to yielding three home runs Tuesday in the Giants' 5-4 exhibition victory over the Milwaukee Brewers suggested that he didn't feel too upset.

"There must have been a home run derby I didn't know about," Bumgarner said in a near-monotone, flashing his dry wit.

Bumgarner's springtime scoreless streak ended spectacularly at the 21-inning mark. He blanked Milwauakee for four innings before Khris Davis pummeled a 3-0 pitch almost to the scoreboard in the back of the left-field picnic section with one out in the fifth inning. One inning later, opposing pitcher Wily Peralta and Carlos Gomez added homers.

Bumgarner, the Giants' Opening Night starter next Monday against Arizona, remained confident after his 5 2/3-inning outing.

"I felt pretty good about the way I threw today," he said, adding that he had no complaints about the pitches to Peralta and Gomez. "They got in their counts and hit the ball."

Paradoxical as it may seem, the left-hander also welcomed the end of his shutout streak, since it would have been impossible to maintain once the regular season began. Save the zeros for when it counts, Bumgarner figured.

"I don't want to give up runs, but it's kind of a relief to give up runs there, if that makes any sense," he said.

Scutaro gets nerve block for cranky back

PHOENIX -- The Giants announced Tuesday that Marco Scutaro received a diagnostic nerve block for his ailing back, a procedure that probably will put the second baseman and No. 2 hitter on the disabled list to start the regular season.

Scutaro, 38, appeared in just one exhibition game, a three-inning stint against the Angels on March 17. Though he has performed light baseball-related activities, the combination of Scutaro's lack of preparation, his lingering back problems and the proximity of the regular season likely will force him to be sidelined.

The Giants were expected to share further details about Scutaro's condition Wednesday, though manager Bruce Bochy said surgery had not been discussed.

If the Giants place him on the disabled list, his assignment can be retroactive for 10 days, so he could miss a minimum of five regular-season days -- which would be only four games, since the Giants are idle when the season officially begins Sunday. San Francisco opens its 2014 campaign at Arizona on Monday.

A nerve block is a procedure in which a specific nerve or group of nerves that could be causing pain are numbed.

The Giants had hoped they'd regain a healthy Scutaro who could hit with authority, as he did in 2012. He drove in 44 runs in 61 games and batted .362 after being acquired in a late-July trade from Colorado, then hit .500 in the National League Championship Series against St. Louis to win Most Valuable Player honors.

Prospect Law still in contention for Giants' bullpen

SCOTTSDALE, Ariz. -- Derek Law figured he would be among the first or second wave of players sent to Minor League camp.

Yet he hasn't pitched as if he had modest expectations.

Law, ranked by MLB.com as the Giants' No. 10 prospect, remains on the active spring roster, possessing a legitimate shot at making the Giants' Opening Night roster. The right-handed reliever has demonstrated the repertoire that stunned club officials during last year's Arizona Fall League, where he made 11 appearances and didn't allow a run in 12 1/3 innings.

Law's competing with left-hander David Huff and right-handers J.C. Gutierrez, Yusmeiro Petit and Jean Machi for one of the remaining three spots in the bullpen. Petit appears to be a lock, and Huff lowered his ERA to 1.13 with a scoreless seventh inning Tuesday. Law had a 1.93 ERA until he yielded two runs in one-third of an inning Sunday against Kansas City to inflate his ERA to 5.40, but he recovered Tuesday by recording the save in the Giants' 5-4 victory over Milwaukee.

Even if Law begins the season in the Minors, he's likely to wear a San Francisco uniform at some point this year.

"He has the equipment to pitch in the big leagues," manager Bruce Bochy said of Law, who benefits from a deceptive delivery in which he turns his back to the hitter. His 94 mph fastball and variety of breaking balls also help, as proven by his six strikeouts in five innings.

At 23 and with three years of professional experience on his resume, Law remains genuinely humble. Asked if he envisioned he'd still be competing for a big league job this late in the spring, he replied, "Honestly, no. I just expected to come here and get the experience of being around all these guys. It's a great opportunity. I'm just enjoying the moment."

Law said he's trying to avoid placing undue pressure on himself to make the team, though he admitted he "tried to have an incredible inning" against Kansas City, which led to his poor outing.

A chat with closer Sergio Romo, who has weathered similar disappointments, buoyed Law's spirits.

"It's always a learning experience," he said. "You learn from it and bring it to the next outing."

Worth noting

Buster Posey started at first base Tuesday for the first time this spring and handled the position smoothly. He made a difficult catch on Wily Peralta's third-inning foul popup before deftly plucking shortstop Ehire Adrianza's low throw out of the dirt on Jonathan Lucroy's fifth-inning grounder.

Michael Morse, who hasn't been tested much defensively in left field, made a nice sliding catch on Rickie Weeks' fourth-inning line drive. "I think he feels he's over the [right] calf issue," Bochy said.

• Bochy said third baseman Pablo Sandoval likely would not play in Wednesday's Cactus League finale against Colorado due to a "gash" in his hand. Bochy indicated the mishap was not serious. Except for Sandoval and Scutaro, the entire projected lineup is expected to start.

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.