Instead he's shipped out and our seventh defender is Duffy, who I love but, well, he's not best suited to Potter's style of play. So with Ostigard being shipped out on loan it suggests he's bellow Duffy, a player deemed not good enough last year, in the pecking order.
You do also need to consider the wage costs, though.
If we keep Ostigaard AND Duffy here for the season, then we have to pay all of both salaries.
If budget constraints mean that we don't wish to allocate funds to pay the full salaries of TWO covering CBs, then one needs to go on loan. If nobody wants to take Duffy, that affects your decision making.