I have heard from my colleagues these last few years that the students are less mature, less able to navigate social relationships, less adept at settling squabbles in class and at recess.

Thank you for the thoughtful answer, Peter.  I have heard the exact same from my teacher clients regarding the above excerpt.  And, you're right, too many confounding variables to know for sure.  Probably why I ask those who trust their eye and care to intuitively disentangle the factors and wage a guess.  All good thoughts and ideas.