Here are his minor league numbers (courtesy http://www.thebaseballcube.com/playe...h_fields.shtml
, which unfortunately also lists the batting stats of the 'other' Josh Fields):
185 G (no starts)
16-14, 36 SV, 2.85 ERA
Not a thing wrong with that, and I don't see why he didn't move more quickly up the ladder. He'll be 25 this year, so his time is now.