The Red Sox' last pick of day three of the 2016 MLB Draft is Santiago Espinal, their first Junior College player of 2016.
Espinal is a player with one clear limiting factor: power. He's never going to hit for much of it, but he can at least make contact, and then do some work on the basepaths once he reaches thanks to his above-average wheels. It sounds like he should stick at shortstop or, if that doesn't pan out, at least be able to move to third, as the arm should play there.
Baseball America has Espinal as the 409th best player in the draft class, which would normally leave him some 100 spots off. But really, once we're down to this point, everything is much more up-in-the-air. Coming in at #400 for BA isn't necessarily all that much better than coming in at #300 or worse than coming in at #500. And it ends up coming down to who the organization is most familiar with and sees something worth taking a shot on.
For Espinal, it's easy to guess what the Sox are hoping for. You might look at what Mauricio Dubon is doing right now as the sort of blueprint for Espinal as a slap-hitting infielder with good defense and good speed. If he can learn to take his walks (he ranks 84th in the FCSAA compared to 4th on batting average) and force pitchers to throw him strikes, he'll be able to hit them, and at least get on base a good bit. You can't expect much out of a tenth round pick, but he at least has some of the tools that could produce an MLB player.