With just a month until pitchers and catchers report for spring training, most of the heavy lifting of the winter has been done. There are a few solid free agents left in Michael Bourn, Kyle Lohse and Rafael Soriano, and there's still a Justin Upton trade out there to have, but on the whole, most of the biggest opportunities have already been taken. It's a zero-sum game, so one team's improvement comes at the misfortune of other teams. While there's still time to move the needle a bit, it's clear which teams didn't take advantage of the opportunities present in the offseason. Here are my top five.