The Oakland Athletics over the Kansas City Royals
The Oakland Athletics were just one loss (and a Mariners victory) from missing the postseason altogether, but a 4-0 win over the Rangers sealed the deal. On July 31, they had the best record in baseball, but a questionable trade of Yoenis Cespedes to Boston has caused them to have the fourth-worst record (tied with Twins) since. Tonight, Jon Lester (the return in the Cespedes trade) goes for Oakland, who's roster is too talented to lose this game.
As for the Royals, they have an ace in James Shields going too, and this is their first postseason appearance since 1985, so the crowd in Kansas City will definitely be on their side and try to help them in any way possible. The reason I can't pick them in this game is due to the lack of postseason experience in their lineup. Shields has some, but other than that, almost all of their homegrown players (which is most of their lineup) weren't even born the last time the Royals made the playoffs.
The San Francisco Giants over the Pittsburgh Pirates
The San Francisco Giants have had to overcome a lot this season to even get to where they stand today. They battled injuries; poor play from the second base position, a spot they even used Dan Uggla (!!!) in; and tough competition this season. Tomorrow, they have Madison Bumgarner on the hill, perhaps the most underrated ace in the game. Bumgarner has postseason -- and World Series -- experience and there is nobody in the Giants' staff that I'd rather have be pitching in this game.
As for the Pirates, almost their entire roster has postseason experience. Even the guy on the hill, Edinson Volquez. Volquez was signed to a one-year, $5 million "prove it" deal this offseason and he has done exactly that. He won 17 games back in 2008, but still hasn't been able to live up to his potential. This year, he's pitched pretty well, posting a 3.04 ERA in 32 games (31 starts). The fact that scares me is that he has a 5.09 ERA in 85 games (84 starts) from 2011 to 2013. We'll see how he does, but I'm skeptical if he can repeat his performance in one game tonight.