I don't think a .060 IsoD in AAA at 21 is all that bad. In fact, while we've all lamented Pie not walking a ton, that .060 is pretty constant through his minor league career. Considering his age and levels, that's okay with me, and I don't think it's necessarily a red flag. Will a walk rate that low keep him from being the next Miggy Cabrera? Yes, but it's not going to keep him from being a good or even very good player. Heck, take Murton, who is widely heralded for his approach, was only slightly better IsoD wise(.071 to .059) at an older age for his levels.