This is a simple problem and I'm hoping someone here has a simple solution. I've been rigging something, and in the below image I've isolated a single eye from the model along with the nurbs controls.

Right now the only thing I can do from here is manipulate the Scale Y value from the slider. Here's what it looks like if I do that:

I want to get a sort of "angry eye" expression, and I'm wondering how I might be able to rig for this. I can achieve the look I want by selecting these faces...

...and then moving them a little bit down with soft-select on, so that it looks something like this:

How can I set up a rigging that allows me to do this? Preferably so that I might be able to achieve a range of values between the first expression and the last.
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