The true story is in performance per screen where BBM is doing @ 160% of Narnia's numbers. And, Narnia is in 3600 more theaters than BBM.
I had this discussion last week when BBM was in a few dozen theaters and was pulling in $10-12K per theater. Now it's in 200+ theaters and it's pulling $2-3K per theater.
It's in enough venues now that pretty much anyone who wants to see it has a theater reasonably close. If it turns out to have some legs, it may cover the $16M production cost, or a bit over. But that remains to be seen; in its 1st week it was the #8 grossing film, now it's down to #14.