The Royals have the power of grit on offense and the grit of power in the bullpen. Also, Lorenzo Cain is a heck of a player.
1. The rotation
You've been following along to this point, so you've probably figured out by now that the Royals can pitch. The rotation has James Shields, top-of-the-rotation workhorse, as well as rookie Yordano Ventura and mid-rotation assets Jason Vargas and Jeremy Guthrie. The back-end isn't sexy, but they limit runs and can pitch deep enough to get to the bullpen -- with all possible games in this series coming in pitcher-friendly parks, too, Guthrie and Vargas likely have their one weakness mitigated. That's key for more than the obvious reasons, because one of the only areas where the Giants clearly surpass the Royals is in power.
If for some reason one of these starters come up lame and can't take their turn, Danny Duffy, who was better than anyone besides Shields on the staff this year, is in reserve. Well, maybe. No one is quite clear on why he's not pitching, but we do know he's not hurt according to the Royals themselves.
2. The bullpen
It doesn't stop with the rotation. If the Giants are lucky enough to bounce any of those four from their starts early, the Royals can counter with a lengthy bridge to mega-closer Greg Holland. They've got Kelvin Herrera and Wade Davis for the seventh and eighth innings, and that duo has combined for 17-1/3 innings with a 1.04 ERA and 20 strikeouts four walks this October. Brandon Finnegan, fresh off the College World Series and being drafted, allowed one run in the majors in seven innings and has held his own in the postseason. Jason Frasor is basically a forgotten name in that pen, but he's quietly pitched fantastically when needed both down the stretch after coming over from the Rangers and in the playoffs. The Giants have a good bullpen, especially with Yusmeiro Petit all stretched out for a starter's workload, but the Royals' is transcendent and unfairly deep at this late stage of the season: it's a huge reason why Kansas City has been able to win all of these close and extra-inning games this month.
Oh, and Ned Yost finally broke his habit of making himself and the Royals wait for the seventh to use Herrera in a Strictly Defined Role. Instead, he called on him at an appropriate time in the sixth inning in the deciding game of the ALCS. In case you need 90s references in order to process everything you read: The Giants are Shooter McGavin, and Ned just learned how to putt.
Wade Davis (Jesse Johnson-USA TODAY Sports).3. Lorenzo Cain
Well, not just Lorenzo Cain: As superhuman as he's appeared these past few weeks, that's a lofty expectation to pin on anyone not named David Ortiz or Barry Bonds or whomever else you can think of that posted better than a 1900 OPS in the World Series this century. Cain has been the highlight player in a Royals defense that just can't seem to stop making ridiculous catches. He's ranged across the outfield for stellar grab after stellar grab, diving, sliding, and running down anything hit in his zip code. He's also been the highlight player in the offense, even if a lot of it has just been well-timed singles: that's basically been their offensive philosophy the last few weeks, and Cain won the ALCS MVP award for his representative efforts on both sides of the ball. The Royals' pitching is great even without this kind of boost, but this is precisely the kind of play that'll push a team to a championship in October.
4. The Little Things
Lorenzo Cain sacrifices in Game 4 of the ALCS (Peter G. Aiken-USA TODAY Sports).
I promise this isn't going to turn into a lecture on the power of grit or anything. The run environment in baseball keeps shrinking, though, so being able to push across a run here and there with speed and bunts and hit-and-runs and the like can make all the difference -- especially when the pitching backing this strategy up looks like that of the Royals. It's not the early aughts anymore: teams can win with an entire rotation and bullpen doing the heavy lifting and the offense doing just enough to not waste the pitchers' efforts, and that's what's brought the Royals this far.
The Giants clearly have the better offensive team, but that's been the case with everyone the Royals have faced both in the regular and postseason in 2014. If the Royals continue to play like they have since a switch flipped in early August, they'll be hard to stop once again.