I think looking at their attributes, Micah should be much better than zaba but for some reason zaba is always there equal to or sometimes even outshining micah.
I think Micah is faster, stronger, more powerful, better in the air, better positionally (arguably) and is a true city man through and through. Yet Zaba is just so consistent and I think he just eclipses micah in one on one tackles. They both make similar attacking runs (although i still think richards is better attacking-wise) and are both versatile (micah plays CB and zaba can play LB).
On any given day I would take richards, but over a season zaba is easily just as influential. I just think we are blessed to have them both...