I think I've located 2 of the Cubs problems.....(1)they peaked early....(2)they quit scoring as many runs.

Proof?

Month by Month
Split           W   L      RS      RA     WP
March           0   1       3       4    .000
April          17   9     168     116    .654
May            18  11     148     109    .621
June           15  12     133     122    .556
July           15  11     128      99    .577
August         20   8     163     104    .714
September      12  12     112     117    .500


The Astros were peaking until that awful cat 3 cane hit SE Texas.
Still think Houston would have at least tied for the WC. 
IKE cost them at least 2 games, maybe 3.