You are correct, the whites went from green letter/number to black and the blacks went from green number to white (names stayed the same). However, there were two other changes on the 2011-12 jerseys from the 2009-11. 1) The Vector logo on the back, above the nameplate, was removed; 2) The WCHA patch moved from the "tail" to the chest.
So, even though the name/number colors didn't change on the green jerseys, it's still a different sweater technically...and I'm a rube.