I hope the Reds hold on to Tanner. Suddenly the Reds are left with very little at AAA for rotation depth. He was a 3rd round pick in 2007. He was nothing great, but at least he came into last year as one of SF's top 30 prospects and his minor league numbers haven't been awful. He's only 23, he's a lefty and being from Australia may make him a little bit of a late bloomer compared to others. I prefer him at AAA to some 28 Y/O career minor leaguer. All the other guys slated for AAA look like they are well past any prospect days.
Heck, I'd stick him on the 40 man roster. I don't really see anyobdy who isn't already on that they absolutely have to add. Maybe H-Rod. Not really any others.