Why would you draft Bart and trade Grullon, a plus defensive catcher who's already put up 10 dingers, the last few on the road?
I'd rather marinate Bart behind Grullon, and see who looks ML ready in two years. Bart is already 21, and would probably got to Williamsport, then A ball at 22, and maybe Reading at 23. By that time you'd know if Grullon is for real.
Both Grullon and Bart are essentially catcher only, since they lack the athleticism for any where else but 1B.
If either one pans out, Alfaro can play 3B or RF as well as catch and get his PAs.