Is there a reason that all these guys are position players?
I may also be interpreting their system wrong, but I think there was an extra filter toggled in that data set somewhere (hit tool=45 FV). I removed it and am now seeing considerably more FV 45 guys among that 2017 list — 186 of them if I counted right.
I’m seeing this list here:
https://www.fangraphs.com/prospects/the-board/2017-prospect-list/summary?sort=-1,1&type=0&filter=&pg=6&pos=&team=
Quick scan, there are plenty of solid major leaguers, including as you said Teoscar and Nimmo, but also Jazz Chisholm Jr., Mitch Haniger, Yandy Diaz, Steven Brault, Dillon Cease, Harrison Bader, Chris Paddack, Luis Urias, Tyler Mahle, Eric Lauer, Chad Green, Mitch Garver, Jordan Montgomery, Jose Treviño, Trent Grisham, Will Smith the catcher, Gavin Lux, Ryan Mountcastle, Trey Mancini, Keibert Ruiz, Dan Vogelbach, Dillon Tate, Lourdes Gurriel Jr., Rowdy Tellez, Brandon Marsh, Jorge Lopez, Josh Lowe, Chad Pinder, Mitch White, Austin Barnes, Robert Stephenson, Ty Blach, Mauricio Dubon, Keegan Akin, Tomás Nido, Gilberto Celestino, Tyler Stephenson, Paul DeJong, Dane Dunning and Rhys Hoskins.
There are others among them who have seen major league time, and a few (like Nolan Jones) who are just now breaking in. But that’s a quick list of guys I count as “useful major leaguers” (with a broad range of values among them, surely). That list is 43 names out of 186, so roughly 23 percent.
Edit: In other words, we’d be lucky if three of Wikelman Gonzalez, Josh Winckowski, Connor Seabold, Mikey Romero, Ronaldo Hernández, Brandon Walter, Gilberto Jimenez, Ceddanne Rafaela and Miguel Bleis had solid MLB careers.