Here are some of the guys that I think fit your criteria. Some of these guys are/were known but they are currently falling outside of the top 100. A few might make it inside the top 100 but I don't obsess about these top 100 lists and by the time most sites release them I've read all about the prospects and formed my own opinion.
I almost completely rebuilt my farm system after 5 big trades that gutted it (Myers, Bogaerts, Sano, Arcia, Skaggs, Cecchini (BOS), Heredia, Hedges, Odor, Ventura and Hedges). The starred guys are mine that were 'mostly' picked up in the offseason. I have mostly went after rk/A ball types with good upside. You hit on a couple and you throw the others back and replace with others. All but one guy is owned in my league (24 tms and 15 MiLB slots).
*Ethan Martin - yeah that guy
*Jorge Polanco - he's such a sleeper that he can only hope to be a fringe top 100 at the end of the year
My website - The World Is Not That Big