The logic goes like this: Active learning works. We would like more faculty to use active learning (and evidence-based teaching methods) in their classes. So, we pair them with people who do use these for a semester (i.e. put them both in the classroom all semester). And voila!
Our promising results are that faculty keep using these same effective teaching techniques, and even that they sometimes transfer them to new contexts.
See also: Some interview results reported in Paired teaching for faculty professional development in teaching.