See:

>If the said process takes exactly 1 year to complete, and requires all the inputs to be provided upfront, then its margins can be directly compared to bond yields, but businesses are rarely that simple.

Something tells me the xbox division isn't some sort of machine that takes in $x in costs at the start of the year and spits out $1.03x in revenue at end. Capital costs could be higher (eg. game takes 4 years to develop before you can sell it), or lower (eg. you pay foxconn $400 to make an xbox then immediately turn around and sell it to best buy for $450).