Everything offensively that the Giants faced with the Reds, they're going to face with the Cardinals…but taken to the next level. The St Louis offense is much more potent than the Cincinnati offense, hitting nine more extra base hits against the Washington pitching staff than the Reds did against the San Francisco staff. The Cardinals also didn't struggle nearly as much with runners in scoring position like the Reds did, posting an OPS 200 points higher and scoring twice as many runs. Whereas the Reds blew many chances to finish the Giants, the Cardinals battered the Nationals in two of their wins in the series, and had an epic comeback to win the third.
The Cardinals bullpen is a lot like the Reds bullpen, in that it's very good and you're not going to go crazy in scoring runs against them. The Giants' bullpen was also very good in that regard, but there's still the possibility that Tim Lincecum, their most effective reliever in his two outings againstt he Reds, will be replacing Barry Zito as the game four starter in the series. Madison Bumgarner starts game one for the Giants against Lance Lynn, and Bumgarner hasn't started in a week. He's very well-rested in comparison to Lynn, who had three relief appearances against the Nationals and was actually a walkoff loser in game four of the series. But Lynn's arm hasn't exactly labored aside from a 50 pitch outing last Monday in game two, so he won't be extremely drained. Fatigue for starting pitchers won't be much of an issue in this series (unlike the American League), due to the extra day off between the end of the NLDS and the beginning of the NLCS.
St Louis looked downright scary in their series against the Nationals, outscoring Washington by 16 runs over the course of their series and losing by just a run in their two defeats in the series. The Cardinals are a very opportunistic team (discounting game one), and if a Giants pitcher has a start like Ryan Vogelsong or Barry Zito did in the NLDS, the Cardinals won't let them off the hook and let the Giants escape with a win.
The Cardinals lineup isn't loaded with dead outs like the Reds lineup was. This is a team that gets hits from all spots in the lineup. San Francisco needs help in their lineup, because a .606 OPS just isn't going to cut it. Aside from their six run fifth inning in game five against the Reds, the offense was a no-show. That was a game that they should have lost with as many chances as the Reds had to win, but they escaped with a victory. Those types of situations won't come up with the Cardinals, and gambling on an offense hitting a cold spell like the Reds did for a second straight series isn't a good strategy to have in the playoffs.