Back-to-back-to-back homers help Giants overcome Madison Bumgarner's struggles

MILWAUKEE, Wis. -- It wasn’t Madison Bumgarner’s best day on the mound, but fortunately for him and the San Francisco Giants, it didn’t need to be. Backed by some mid-game defense and a whole lot of offense, Bumgarner got an Opening Day victory as the Giants routed the Milwaukee Brewers 12-3.

The offensive onslaught was highlighted by the Giants' hitting back-to-back-to-back home runs in the eighth inning, when Denard Span, Joe Panik and Buster Posey all went yard against righty Ariel Pena to turn the game into a laugher.

Turning point: The game initially looked like an even slugfest with the Giants leading just 5-3 heading into the bottom of the fourth, but there the defense saved Bumgarner from additional damage when first baseman Brandon Belt dove to snare a sacrifice bunt attempt by pitcher Wily Peralta to advance Scooter Gennett. That base saved the Giants a run when Gennett was subsequently thrown out at home by left fielder Angel Pagan while trying to score from second, a play that ended the inning.

What it means: Opening Day or not, it was just one game, played against a Brewers team that won’t wind up among the league’s best, but on a day when the Giants’ ace wasn’t at his best, their offense showed the kind of depth to outscore any starting pitcher’s rough day at the office. It also was important for the Giants to get some sort of happy news concerning Bumgarner after their ace missed a spring turn because of minor foot and rib injuries and then battled the flu before his Opening Day start. Spotted a 7-3 lead, Bumgarner exited the game on a high note by striking out the side, swinging, in the fifth.

Thumbs up or thumbs down: A big thumbs up for Giants third baseman Matt Duffy and center fielder Span, who became the first Giants since Barry Bonds to notch four RBIs on Opening Day. And another thumbs up for Belt for doubling in the second after failing to get down a bunt, as well as that sweet defensive play in the fourth. And a thumbs up for journeyman lefty Chris Capuano, whose inning pitched for the Brewers marked his return to the organization he spent 2004-2010 with, including an 18-win season in 2005.

If you have to give anybody a thumbs down on Opening Day, give it to Brewers righty Pena for giving up those three home runs to consecutive batters in the eighth. And maybe another thumbs down for Span’s throwing arm, because on normal chances the Brewers tagged up and ran on him going from first to second and second to third.

What’s next: After investing $130 million in Johnny Cueto as a free agent, the Giants need to see if he can provide them with some instant good news for their rotation in his regular-season debut on Tuesday night while going up against hard-throwing Jimmy Nelson of the Brewers.

Christina Kahrl writes about MLB for ESPN. You can follow her on Twitter.