After winning the 2010 world series the Giants had high hopes of returning to the playoffs, in hopes of another title run. Unfortunately they didn't even make the playoffs. They were had a strong pitching staff, led by Tim Lincecum. The offense was towards the lower half of the league, but with Buster Posey returning, they should get more run production.
Offensively Pablo Sandoval was the teams best producer. His .315/.357/.552 (142 wRC+) was a career best, and he did that in only 466 plate appearances. He had a 12.3 UZR, which is a huge improvement from years past, but he most likely isn't that good defensively. Overall he managed to amass 5.5 total WAR. Assuming he stays healthy, and plays good defense he can easily be a 3-5 WAR player the next few seasons. Aubrey Huff is penciled in as the starter, but if I had to guess I would say Brandon Belt starts the season at first. Brandon Belt's first stint in the majors didn't go exactly as planned, he showed signs of power, but struggled with strikeouts. He has the potential to hit 20 home runs, and if he can put it together he could potentially be a 3-4 WAR player for the Giants.
Three guys will all get a chance to play the middle infield. For now Freddy Sanchez will start at second, he's known more for his glove than his bat, but last year he missed a lot of time. Offensively he will most likely be slightly below average to average, but if he can supply above average defense he can be a 1-2 WAR player. Brandon Crawford will play short, and from what we have from last year he wasn't that great. His offense was well below average, but if he can have some value on defense he may stick around. If all else fails Mike Fontenot can take over. He's had some nice defensive seasons, and can play shortstop or second base.
Before Buster Posey injured his leg he was on his way to another fantastic season. During his rookie of the year campaign he posted a solid triple slash line of .284/.357/.505 (114), all together he had 3.9 WAR. Assuming he bounces back he should be able to be a 3-4 WAR player, with 5-5.5 WAR potential.
In left Melky Cabrera is coming off a career year where he posted 4.2 WAR, which was largely due to his offensive production. e was largely helped by a .332 BABIP, that's unlucky to repeat this season so expect some regression. He's probably closer to a 1-2 WAR player, not a 3-4 WAR player. Angel Pagan is the new center fielder, after coming over from the Mets. He had a 5 WAR season in 2010, but regressed to his normal rate. His BABIP was .285 which is a little low compared to his average, if he can have a BABIP in the .305 range he could be a 2-2.5 win player next season. Nate Schierholtz rounds out the outfield, and he's not much better. His offense wasn't terrible last year, but he was a liability in the field. He's much better suited as a fourth or fifth outfielder.
The starting pitching is the real strength of this team though. Tim Lincecum had another good year, posting 4.4 rWAR. For the second year in a row he saw an increase in his walks, and a decrease in his strikeouts which is something that may be a cause for concern. On a positive note he saw his HR/FB% decrease, so if he can keep the walks from becoming a problem he should be okay. Matt Cain had another good year himself, he had 3.9 rWAR and also saw his home runs decrease. Like always he out-pitched his peripherals again, that should be expected again this season. Madison Bumgarner continued his process of becoming an above average pitcher. He saw a 5% increase in his K% while maintaining his steller BB%. He is probably due for a little regression, but he's still a stud.
At the four spot Ryan Vogelsong came out of nowhere and had 3.7 rWAR. His 2.71 ERA wasn't his true talent level though, he's probably much closer to his 3.85 xFIP and 3.97 SIERA though. That still makes for a nice number four pitcher. Barry Zito had another disappointing season where he had -.6 rWAR. Luckily for the Giants they only have two more seasons of him until he's gone.
The bull-pen is highlighted by Brian Wilson, and his beard. He struggled somewhat last season, but should bounce back this season. Sergio Romo is a pitcher who is someone to watch, he struck out 40% of the batters he faced last season, while walking only 2.9%. Obviously there is regression that will take place, but he's a very good arm nonetheless. Other pitchers to keep an eye on are Jeremy Affeldt and Santiago Casilla.
If the Giants want to make the playoffs they will need their pitching to have another excellent year. Tim Lincecum needs to make sure his K% doesn't continue to fall, and obviously stay healthy. The line-up needs to do much better than last season, Brandon Belt needs to further develop and Posey needs to get back to his 2010 level. If this team can accomplish that they have a good shot at the playoffs.