I think Red Bird Nation sums up the difference between the Cubs and the Cardinals.

For the most part you have to squint your eyes to see any big difference between these two teams. Except for one area: walks. The Cards are 8th in the league at drawing walks (i.e., average), but the Cubs are all the way down at #13. The difference is even more dramatic on the other side of the ball -- the Cubs have given up the 10th most walks in the league, while the Cards are the stingiest in the NL.

The Cardinals draw more walks which creates more scoring opportunities. On the pitching side the Cardinals walk fewer batters which means less damage in big innings even though they dont SO as many as our vaunted staff.

Meanwhile the Cubs don't get enough runners on base which means less scoring chances, and the pitching staff allows a great many base runners which lead to the big inning and more chances for the opposing offense to score in key situations.

The Cubs can live with the walks from the pitching staff but not the offense. If this team was simply more patient at the plate they would be a more consistent offense. Not perfect, but better. Add in a lefty/righty balance and you start getting near perfect.