We’re looking for perfect fits — something like the Red Sox got by signing J.D. Martinez last winter. Big-ticket free-agent signings seldom work out so perfectly: A team that was already very good got a guy who made them even better, on the field and in the clubhouse. And they jumped on duck boats and rode off into the sunset with a World Series trophy. Yeah, those kinds of fits. We’re working up our list and checking it two and three times more.