Friday is a big day around baseball, as today marks the final day teams are allowed to add prospects to their 40-man roster in order to protect said players from the Rule 5 Draft. We’ll get into what all that means in a second, but on just a broad, basic level the Red Sox will be making roster changes today. Exactly who is added, who is removed and whether it’s done via trades, waivers or a combination of both remains to be seen. But in an offseason that has been extremely quiet on the player side of things for the Red Sox, today is a day that guarantees at least a little movement on the bottom-half of the 40-man roster, and perhaps more than that as well.