And now look at them.
They are battling to not only avoid a last-place finish in the NL West, but are on pace for the second-worst encore to a World Series championship.
The Giants went into Saturday at 60-74, tied for last place in the division with San Diego, and with the worst winning percentage (.448) of a defending World Series champion other than the Marlins, who went 54-108 (.333) in 1998 after winning it all the year before.
The Marlins, however, weren't caught off guard. As the parade to celebrate the World Series championship was ending, the Marlins' owner at the time -- H. Wayne Huizenga -- was ordering a gutting of the team's roster and slashing the payroll.
Not so with the Giants. They came into the season planning to contend again, carrying a $142 million payroll, which ranked sixth in baseball, according to the Associated Press.
"This has been tough on everybody," said manager Bruce Bochy. "We didn't see this coming, as far as struggling in all facets."
A Giants team that prided itself on an overpowering rotation in which the "Big Five" combined to start 160 of the 162 regular-season games in 2012 has already used 10 starting pitchers. The Giants rank 21st in Major League Baseball with a 4.11 staff ERA, and the rotation ranks 24th at 4.47.
The Giants also have scored 505 runs, more than only Miami (420), and have a .981 fielding percentage that ranks ahead of only Milwaukee among the 30 Major League teams.
"The defense is the most frustrating," said Bochy. "We've made fundamental mistakes that have cost us games. That's been the biggest frustration -- not showing up every day."
The Giants do have a chance to undergo a major offseason overhaul. They have close to $60 million coming off their payroll this winter, although they could have to scramble to rebuild the rotation. Tim Lincecum, who is making $22 million this season, is in the final year of his contract, and there are buyouts for Barry Zito and Ryan Vogelsong.
The Giants are currently on pace to become only the 15th defending World Series champion to finish below .500. Among the previous 14, the Marlins' .333 winning percentage in 1998 was the worst, followed by the '91 Cincinnati Reds (.457), '18 Chicago White Sox (.460), '32 St. Louis Cardinals (.468) and '86 Kansas City Royals (.469).
No franchise has gone from a World Series championship to a losing record more than once except the Cardinals, who not only did it in 1932, but also in '65 (80-81), '83 (79-83) and 2007 (78-84).
At 26, Wladimir Balentien decided to give up his Major League dreams and take his baseball career to Japan. He has been a hit in his three years with Yakult -- maybe too big of a hit.
After clubbing 31 home runs each of the past two seasons, Balentien went into Saturday with 52 homers, three shy of the Japanese professional record originally set by Sadaharu Oh in 1964.
The question is whether Balentien will be given a chance to break the record. Foreign players haven't been given the opportunity in the past, according to Burly's Baseball Musings.
In 1985, Randy Bass had 54 home runs with one game to play. He was intentionally walked four times by Yomiuri, the team Oh had played for and was managing at the time. Sixteen years later, Tuffy Rhodes had tied the record for Kintetsu and was intentionally walked in the final three games against a Fukuoka club managed by Oh.
Alex Cabrera tied the record the following year with five games to play, the final three against Fukuoka, still managed by Oh. According to Burly's, "Oh claimed to have instructed his pitchers not to walk Cabrera, but most of the Hawks pitchers nonetheless threw Cabrera nothing but balls well off the plate."
Balentien, a native of Curacao, never reached his homer potential in the Major Leagues. He hit 147 home runs in 682 Minor League games, with a high of 25 with Class A Inland Empire in 2005. Balentien also hit 15 home runs in 559 big league plate appearances spread over 170 games from '07-09.
• The Rockies went into Saturday with a 4.02 ERA at Coors Field, which would be the lowest in franchise history. Colorado has had an ERA below 5.00 at Coors Field only six times in the previous 18 seasons, including a franchise-best 4.25 mark in 2010.
• For the third year in a row, Houston was the first team eliminated from a divisional race this year. The Astros' American League West hopes officially ended Tuesday. They were eliminated from the AL Wild Card competition on Wednesday. Miami became the first NL team officially eliminated from a division title on Thursday.
• Boston could become the seventh team to go from last place one year to a division title the next since each league went to three divisions in 1994. The six who did it were the '97 Giants, '98 Padres, '99 D-backs, 2007 Cubs, '08 Rays and '11 D-backs.
Out of Left Field
During the 18-inning marathon between the D-backs and Phillies on Aug. 24, Clint Fagan became the first umpire known to have been behind plate in a Major League game in which 700 or more pitches were thrown, according to writer Bill Arnold. There were a combined 712 pitches thrown in the game, which included 168 plate appearances, 19 runs, 35 hits, 32 strikeouts, 28 walks and 44 players. Fagan, who is in just his third year as a substitute umpire, was working his 89th big league game since 2011.
The previous pitch-count high since 1989 (when pitch-count tracking officially began) was 658, when Alfonso Marquez was behind the plate for Colorado's 22-inning victory at San Diego on April 17, 2008.