Cubs OPS Differentials By Month

These are in the table below. The Cubs hitters had an OPS of .796 in April while their pitchers allowed an OPS of .576 (POPS). That differential was .220. The best ever for a full season from 1914-2014, using the Baseball Reference Play Index, was .196, belonging to the 1927 Yankees. See my post The 25 Highest And Lowest Team OPS Differentials From 1914-2014.

Month	OPS	POPS	Diff	Comment
April	0.796	0.576	0.220	Better than 27 Yanks, the best ever
May	0.764	0.606	0.158	As good as 39 Yanks, 2nd best ever
June	0.792	0.629	0.163	See above
July	0.804	0.910	-0.106	Like 42 Phillies, in bottom 2.5% all-time

The Cubs have only played 10 games in July (they are 2-8). So maybe July won't end up being so bad. Over the last 28 days (24 games), the Cubs hitters have an OPS of .824 and their pitchers allowed .778. That includes the 10 games in July and the last 14 in June. 

The 1939 Yankees had a differential of .158.

The 1942 Phillies were the 49th worst team out of 2,168 teams. They finished 42-109, good for a .278 winning pct. They were 8th in a league with 8 teams. They finished 62.5 games out of first place and 18.5 games out of 7th place.

The very worst team in OPS differential was the 1954 Philadelphia A's at -.156.