Like the analogy. :-)
I think though regarding left back, many of us just have different expectations of what a left-back does to what Pep wants. I think many want ideally someone like Ashley Cole, overlapping down the left and racing back to make sliding tackles, with nobody getting past him.
But that just doesn't seem to be what Pep wants. He seems to have been happy picking between either a very defensive minded left back (left footed centre-back) or someone good on the ball to invert and help out with ball retention in centre mid.
Just not sure if it's because of theres nobody out there attainable and good enough, so he's making do, or if this is how he wants us to be.