I might be able to shed more light on this subject, or perhaps even raise more questions??
Most of my experience with OH ratsnakes involves SE OH. I would tend to say you can't really attribute the coloration as strictly an E/W thing. I will say I have seen far less in the Western part of the state, but none have been patternless. Whatever that tells you... I have no examples of Central OH, NW or extreme NE though. The many DORs I have seen in the S and SE have been extremely variable.
I guess I should just let the pictures do the talking though.
Not the best picture, but the first one I came across.
This individual had a fairly pronounced pattern.
Vinton Co, OH

Vinton Co, OH another lightly patterned individual

Vinton Co, OH with no pattern

Jackson Co, OH

Vinton Co, OH

Hamilton Co, OH

Columbiana Co, OH (Penn/OH border)

Vinton Co, OH very little pattern

Vinton Co, OH

Vinton Co, OH

Who knows what really is at play here... Is it age, elevation, habitat preferences, genetic flow from out of the mountains to the East or flow from the South and West, etc??
Jason