one immediate question I had, after read the abstract, is how are they going to measure learning result. without looking into the testing material, I'd argue if the tests were not carefully designed, it could produce whatever result anyone likes, by adjust depth/width ratio of the given subject. maybe the testing materials are so well regarded in the field so there would be no justification necessary, but by ignoring the possibility to readers, it feels not trustworthy to me.
back to the explanation of the result, it's entirely possible that learners (and the authors) not able to draw distinctions between information and performance. I'd assume the traditional teaching would expose much more information to students (anecdotes, connections to other fields), but 'active' learning could give better result in performance building in a narrowed domain.
I'll read carefully into the paper sometime later, but for now, it's not a paper I'd recommend. (feel free to downvote if I get anything wrong)