First of all, I did not realize, nor was I aware, that Disney movie division is in a "slump", or as this article puts it "... in the worst slumps at the box office in years.." Wall-E doesn't count?
It is hard to compare with the previous year with an anomaly such as "At World's End". Most studios do not have such kind of success every year. So it is understandable that Disney cannot replicate that. Still, considering what they have in store for the next couple of years (can we say "TR2N"?), I'd say that have a very exciting slate of movies in store, especially with Toy Stories 3 and The Princess and the Frog.