Rabbitz being a huge Cubs Fan and having watched the sport for a few years now I can help you a little.

The pitchers are the main reason for score discrepencies every team has a 5 man Starting Pitcher rotation and because of the way the games are scheduled it doesn't always mean each teams #1 pitcher will go against eachother.

The other reason for the discrepencies could just simply go down to on and off days for the hitters. Alot of guys would get a hit 28-31% of there at bats which leaves alot of other occasions when they don't so that can be another reason.

Another one could have to do with the Relief Pitchers who would come in when the Starters get tired most teams would have 1 or 2 good relief guys and they don't want them to be worn out to early in the season they play 164 games so they have to be careful not to get there Bullpen burnt out early in the season. So with saying that they won't use there best Relief guys all the time.

Hope that helps you out a little.