It starts with Regional Champ and last year placing. If they are tied there then it will go back in years until the tie is broken. So with your scenario, based on the first round of criteria, this year regional champ and previous years placing. The other wins 4th > 6th.
Like I said as I understand the rule, and how it appears to be applied.
So it goes in rounds as far as I understand.
1st round of criteria is (Regional Champ + 2016 state place)
2nd round is (state placing 2015)
3rd round is (state placing 2014)
I don't think it is a combination or a total of all years.