I would believe temperature, except that the Cardinals don't really have that problem and St. Louis gets hotter than Chicago.
The biggest problem is a lack of depth everywhere. I'm with Kittle that the Sox need an all-around utility type of player that is at least decent enough with the bat, that we don't lose much with him on the field. Our bench players this year were a total liability on offense that cost us games and forced Robin to use the same lineup in the hot months of July and August. In the Cardinals case, they have enough versatile players on the bench to survive those hot months.