This included American league teams which have to face a DH. The Cubs have a run favoring park and play in a division that supports some very good offensive teams. They might not be the worst pitching/defense team but they are close to it. I'm going to take a look at the biggest offenders.
First I'm going to focus on defense. The Cubs rate poorly on defense. The worst offenders are Reed Johnson and Kosuke Fukudome. I don't really believe these are bad defenders, either they are poorly positioned or the wind is messing with the system that rates them (UZR). Castro rates poorly too, but it was always questionable if he was going to stick at shortstop or not. He still has time to improve. The rest of the defense is about average, but not good enough to pick up the slack from the aforementioned.
I'm going to do pitching in a seperate entry.