It seems like you might enjoy the article Stupid Tutoring Systems, Intelligent Humans! It talks about some less commonly thought of factors (e.g.emotional) that are important for teaching processes.
I confess I'm more skeptical of "data, data, and more data" than the author (from whence it comes? an A/B test of the video widget we wrote last week? the "anecdotes" of a skilled teacher with decades of experience can surely be more informative sometimes!), but I'm certainly eager to incorporate what good data is available!