Where are you getting your numbers? In terms of runs scored we are at 4.01 per game which is good for 9th in the NL and 18th in baseball. 7th in baseball in batting average with .263 average, and 11th in slugging percentage with .400. We kind of suck in OBP with .313 tied for 18th in baseball. But this is at worst a slightly below average offense.
The Cubs on the other hand allow 5.02 runs per game which is the second worst rate in baseball and worst in the NL. The Cubs WHIP is 1.472 which is the worst in baseball. The Cubs starters have the fewest quality starts in baseball, and have pitched the lowest amount of innings. Granted injuries played a part in that, but the reason the Cubs are this bad is that the pitching is beyond terrible. If the Cubs want to compete next year, improving the pitching has to be goals 1, 2, and 3 in my opinion.