Although I disagree with some of this, I'm not going to dispute it. However you are excluding the human factor. Robinson, Mathews, Lewan and Glenn all believe they are left tackles and should be paid as such. Based on what your saying if they draft either Robinson or Mathews, then Glenn eventually goes to RT, which means in two years he is gone and they are back to looking for a RT. Lewan is not going to be happy about being drafted to spend half his career at RT.