The Giants have had a really awesome second half, going from half a game back in the division at the all-star break to a 10-game lead in the division. I'm sure a lot of this has to do with their schedule, but let's not take anything away from Buster Posey's second half, which, in my mind has earned him an MVP award. On top of that, Barry Zito has been not pathetic for a change, Marco Scutaro has been great, and Matt Cain has paired spectacularly with MadBum to give us pretty entertaining 1-2, even during the "absence" of Tim Lincecum.
While the Giants are, arguably, the hottest team on the NL side of things, there are some pretty significant worries moving forward. First is the rotation, beyond the aforementioned Cain and Bumgarner. Tim Lincecum has been garbage all season, Barry Zito is still Barry Zito, despite pitching respectably at times this year, and Ryan Vogelsong has been absolutely atrocious over his last 10 or so starts. Romo, Casilla and Lopez have been great out of the bullpen all year (Casilla has been a bit fortunate), so the bullpen should be a strong point.
The loss of Melky Cabrera seemed to actually make the team play better, for some reason, despite the loss of a guy who had put up 4.6 WAR in 113 games. Angel Pagan has put up 4.4 WAR this year in a nice bounceback effort (he was traded this offseason from NYM for Andres Torres and Ramon Ramirez in what has to be the most lopsided deal of the year in hindsight), and has filled the void nicely, as had Gregor Blanco, who has
All things considered, it's not a huge surprise that the Giants are where they are. They're clearly the best team in a weak division, but they can definitely get hot and rattle off a few wins in the playoffs, even if they aren't the best team. My main issue is that they'll probably be the worst team on the National League side from a true-talent standpoint. I'd definitely favor WAS and ATL, I'd probably favor CIN over them as well, and STL is probably a pretty even matchup.
I don't believe the Giants are going to be favored to advance past the division series, but they're definitely good enough that I could be wrong.