I went ahead an expanded it to just teenagers in the Pioneer League and went back to 1995. For comparisons I used BB rate, K rate and IsoP.
His close comps were:
Everyone else, including your comps, were just to far away for me. Chris Nelson had 20 walks and 42 strikeouts. Billy Butler had a .220 IsoP (Winker is just at .120). Gindl had just 20 walks and 38 strikeouts while also showing a .208 IsoP.
The problem is with trying to find comps for guys like Winker is that there simply aren't many guys his age to begin with at this level, so the pickings are slim to even look for. Then you get into that he has a pretty unique skillset for his age and it makes it even tougher. Lots of guys at 18 have had some power, but not many come into pro ball with his kind of discipline.