I think Zaba's been excellent past few games and I also agree that his language is a big help when playing alongside Silva, Aguero and Tevez (and other spanish speakers).
I also think that's it's a bit tactical too. If you have both Nasri and Silva, with Aguero and Tevez, you're not so reliant on the full back bombing on, so Zaba has been a bit of an insurance policy because there's no doubt he's a little more disciplined defensive wise than Micah. So if one of the attacking 4 isn't playing for whatever reason, I think Micah plays, but given the past few games, if it isn't broke, don't fix it.
If we beat Newcastle and QPR, and Zaba starts those two games, then Micah can still be rightly proud of the contribution he'll have made.