I see a lot of people expressing this sentiment. First, they didn't give up much for him so I'm not sure why many are acting like he is a major investment. Second, it's not like they could've predicted this offer would be made. But mostly, Rosen isn't on this team for just one year. Barring a trade he will be here next and the year after, and if we don't pick a bunch of busts he can reap the benefits of this trade by being on a better overall team.