Why are ps3 exclusives sellig so badly compared to xbox360?

[Boberman]

GT prologue is over 4 million from the developers website,
Gears and MGS4 both sold 5 million within 3 month of each other so those games are very close ( Each from there respective finacial reports)

So after Halo 3, and gears 1, its basically a wash in for exclusives and how well they sell.