Some X-factors from Bleacher Report:
1) The Giants' Unexpectedly Strong Starters
The Giants starters posted a 1.40 ERA which was 2nd among division series teams. They will need some more of that against the Cards.
2) The Giants' Random, Contact-Oriented Offense
The Giants hitters make a lot of contact—the team's 13.7 percent strikeout rate was the lowest in the division series. So they bounce balls at the defense and hope they get lucky. You really have to earn your outs against the Giants. Can the Cards make the plays the Nats couldn't? That will be vital.