All around - as I read the posts it seemed to me that the answers were going in different directions - maybe it's just me.
They are all saying the same thing, it is just your current understanding of MOA is making it difficult. Let's try to start over and reteach you the basics of what MOA actually is:
What you need to understand first is that MOA = MOA, regardless of range.
1 MOA at 100 yards = 1 MOA at 200 yards = 1 MOA at 300 yards etc....
A basic understanding of the conversion of MOA to inches is that 1 MOA = ~1/100 * range.
As an example I will calculate 1 MOA at 200 yards:
1 MOA = (1/100)*(200) = 2"
And now for 500 yards:
1 MOA = (1/100)*(500) = 5"
Now if we go back to your thought of 189 yards:
1 MOA = (1/100)*(189) = 1.89"
Now, you chart said that you would be hitting 8.3" low of your POA at that range. To calculate that drop in MOA you have to divide your total drop (8.3") by what the value of 1 MOA is (in inches).
It would look something like this:
8.3" / 1.89" (which is 1 MOA) = 4.39 MOA