I have no insider info, but this reinforces my thoughts on Buchner. I suspect he may not have the raw talent of either Simpson or Milroe, but is already familiar with Rees and that probably goes a long way.
I watched some footage of Buchner over the weekend and I was suprised by his wheels. I'd heard he had good mobility but he looks like a very natural and instictive runner, and he's quicker than I would have expected. He wouldn't beat Milroe in a footrace, but he looks considerably more comfortable running the ball than Tua, Mac or Bryce. I also watched a short interview with him from last year's preseason and he strikes me as a very smart dude. His dad went to Colgate and his mom went to Yale.