it's not just early season... In fact, earlier in the year USCF ranked behind Wrigley, Coors, and Ameriquest for HR's/G.
Now, USCF leads by quite a lot. Just take a look at the White Sox Home/Road splits.
Home(USCF)
Sox (64 games) - 111HR's
opponents - 96 HR's
Road (64 games)
Sox - 78 HR's
opponents - 80 HR's