If you didn't change anything else in your recipe I would say that it is the change in flour to high-gluten flour that was most likely responsible for the improved handling qualities. The high-gluten flour, because of its higher protein content and higher gluten formation, will produce a stronger gluten network--one that handles better and is also able to retain more gasses and produce a greater rise. A high hydration percent, along with the oil, will also aid in forming a good gluten structure. Increasing the hydration of a dough will usually have the effect of producing a more extensible dough, in part because a more highly hydrated dough will undergo greater fermentation. Increasing the amount of oil will also improve the handling qualities of a dough because it coats the gluten strands so that they slide over each other more smoothly. I have found that using a small amount of honey will have a similar effect.