My biggest concern about JD Martinez from this article:
"Martinez isn’t a perfect fit because he’s a righthanded opposite-field power hitter. Martinez pulled only eight of his home runs last year. Fenway Park, particularly early and late in the year, does not serve his rightfield gap power stroke well at all."
That's unbelievable. Pulling just 8 out of 45 homers? I'd guess that Fenway would suppress his HR power so that it would be fantastic if he'd hit about 35-37 homers. Don't get me wrong - still a power upgrade, but the Sox would be paying for 45 homers, not 35-37.
EDIT: Then again, there's this spray chart from 2017 with Fenway overlay, and it makes me a little more optimistic:
And in fact, how can the SI article be right in saying that only 8 of his home runs were pulled? I see 18, not 8. And the RF and CF homers would have been out of Fenway except for two, maybe three. So ok I feel a little better.