As best as I can figure, it works like this. Managers get good grades if they sell certain amounts of products.
I'll use low numbers here. Let's say BB corporate wants you to sell at least 5 iPads a day to make your "Quota". One day, 10 iPads come in. You sell all ten, yay, you made quota for the day.
But the next day, none get shipped to the store. So, boo, you didn't make quota, since you didn't have any to sell.
So, if you get 10 the day after that, & not knowing if more are coming tomorrow, you sell 5, make quota, and hold the other 5 for the next day when, low and behold, none get shipped to the store. You still have 5 left over to sell, which you do, and again you make quota for the day.
Basically the more days you make quota, the happier BB corporate is, and the better chance Mr. Manager gets a bonus down the road.
Mr. Manager