this trade is meh, though at least the Padres are on the hook for most of his contract. Hosmer's a glorified Casey Kotchman and has just barely been above replacement level since signing that contract (0.3 fWAR in *five* seasons as a Padre; yes, that's his total), but the sad reality is that he actually represents an upgrade over the shitshow that has been Dalbec/Cordero. I just hope we'll get to see Casas soon.
As for the prospects we got back, they look pretty blah. Rosier has an interesting profile with the walks and steals, but he's a 22 y/o in A+ ball hitting .263/.381/.396 (with 33 steals). Not a lot of power, remains to be seen if he can keep drawing walks in the upper minors. Ferguson is another one with walks and steals but seems to have more contact issues and even less pop than Rosier, plus he's struggled in A+. He seems like filler.
Groome was highly touted when the Sox drafted him but he's been derailed by injuries and his velocity has suffered. He's held his own in AA and AAA but the peripherals aren't great. Groome also seemed like he was destined to go in the upcoming 40 man crunch.