Giants have taken a step back

The San Francisco Giants are facing some significant early-season challenges only eight games into the season.

The Giants were shut out by the Colorado Rockies 2-0 on Monday, extending their losing streak to four games. It was the second time during this streak that they've been shut out (they lost 1-0 to the San Diego Padres last Friday).

The Giants are the first defending World Series champs to be shut out in their home opener since the 1953 New York Yankees.

What are the biggest issues the Giants are currently facing?

They haven't hit when it counts

Most teams haven't hit much this season, so San Francisco is average or close to average in the three slashline stats (batting average, on-base percentage and slugging percentage). But the lineup has lacked punch without Hunter Pence (who is likely out until May) and has struggled with men in scoring position.

Buster Posey, Casey McGehee, Gregor Blanco, Joe Panik and Joaquin Arias are a combined 1-for-25 with runners in scoring position. That's dragged the team batting average in those situations down to .191, which ranks in the bottom 10 in the majors through the first nine days.

The Giants also haven't hit late in games. They went 0-for-9 in the last three innings Monday, dropping their season batting average in innings seven through nine to .177.

Pitching blips

The Giants have gotten a pair of good starts from Chris Heston, but thus far, their veterans have been a little inconsistent.

Ryan Vogelsong allowed seven runs in 4⅔ innings in his first start of the season. He allowed seven or more runs in only one start all of last season.

Jake Peavy allowed four runs in four innings Sunday in his season debut. That looked more like the Peavy who struggled in the World Series than the one who had a 1.35 ERA in his last nine regular-season starts of 2014.

And ace Madison Bumgarner was roughed up for five runs in three innings in his second start. It was Bumgarner's shortest start since June 21, 2011, when he allowed eight runs in one-third of an inning against the Minnesota Twins.

Defense lacking

Entering Monday, the Giants ranked last in the National League in defensive runs saved, and while admittedly that's from an extremely small sample size, there may be at least one cause for concern.

The Giants have missed Pablo Sandoval at the hot corner. Third base is responsible for losing four of the team's negative-7 defensive runs saved.

Though Sandoval wasn't necessarily Gold Glove-worthy, he was capable at the position last season, finishing with four defensive runs saved.

Video scouting services that chart defensive data credited Sandoval with 60 Good Fielding Plays (think Web Gem-caliber plays) and 30 Defensive Misplays & Errors.

Giants third basemen have not made a Good Fielding Play this season, and they've been credited with five Misplays & Errors.

Fighting history

Talk to San Francisco fans and you'll hear of the "every other year" theory with regard to winning World Series, as the team has done so in 2010, 2012 and 2014.

The Giants have made the postseason in back-to-back seasons only once in the past 77 years -- in 2002 and 2003.