Robert_Charlton - 9:05 am on Apr 21, 2011 (gmt 0)
I'm thinking that appropriateness of reading level relates to the query... and that reading level is one of many factors that the algo is taking into account.
I'm also thinking that the algo may be close to being self-calibrating, with user behavior being an important factor (considerations go way beyond bounce rate here), so ease of reading may simply be a reflection of what some users want... all other things being equal. Remember... results are now personalized for many users.
On some queries, I'm seeing that some losing sites appear to use language that's too simple... and on other queries losers appear to be using language that's too advanced. What I'm seeing fits with my expectations of what kinds of queries correspond to different subject matter and reading levels.
I also think that Google is in its calibration mode, crunching through massive data-sets, correlating lots of information before making further adjustments to the algo, and that's most likely why we're not immediately seeing site changes having an effect. As I remember, something similar happened after MayDay.