I don't agree with squad rotation when it comes to CB pairings of any of the back line really for that matter. Tinkering with the back line unless you absolutely have to is a recipe for goals against in my opinion. Communication and knowing the other player's defensive tendencies takes time to learn and you can't just swap people in easy and expect the same results. One miscue can be a goal. That is my two cents anyway. Let the other defenders play when they need to only. If you want to give them game minutes give them a TFC II game here or there if that is possible.