If I understand this correctly, you're de facto saying that there are 31+ corners allegedly better than Butler. I say BS. I don't agree with Miguel that Malcom is a Top 5 but he's most likely in the top 10.
Agree Gilmore is better.
I think length plays heavily into the equation, especially given this seasons schedule, e.g...Julio Jones, Kelvin Benjamin, Mike Evans. Butler is really good against an average size receiver, he struggles against the big guys and Belichick has generally shied away from using him against those receivers and found other ways to deal with them. And if you want top CB money you need to be able to match up and take away those weapons. This in no way means he isn't a really good Corner, he is, but I agree with Pissah that top 10 is a better range than top 5.