I wouldn't be surprised if Hosmer gets some serious BABIP love next year if the shift ban gets put into place. A 58% GB rate is kind of death in the current environment, but could be more useful next year. That said, the studies I've seen haven't shown a huge difference in batting average on GB in the leagues they have put the ban in place, but a huge increase on average of line drives to shallow RF, which makes a lot of sense.
In any case, Hosmer is a huge upgrade on Franchy, a moderate upgrade on Dalbec, and good insurance for Casas not being ready. I am not convinced Casas is ready, nor do I think the organization thinks he is, which is absolutely okay, as he is 22 years old.
Ferguson and Rosier are the kind of guys who might see the same benefit from a shift ban, as well, so I am probably a little higher on them than some others. They also fill a hole in the organization of players with really, really good baserunning ability.
Overall, I really like this deal for the Sox, even if part of me could see Groome thriving in San Diego.