I have a different explanation for the discrepancy. The Columbus Dishrag has had it in for Blackwell from the beginning. They hate the fact that he is a conservative Christian and they are doing everything in their power - including producing what I believe are bogus polls - to defeat him.
Reminds me of the last survey the Columbus Dispatch did a few years back before election day. Their survey showed that 5 left-wing initiatives up on the ballot would pass by 66% of the vote. It seemed that conservatives should simply stay home. The Dispatch codified that we had already lost.
Oddly, most liberals must have had car trouble that day, since in the only unspinnable poll- the election itself- the measures were defeated by 66% of the vote, indicating a margin of error for the Columbus Dispatch of plus or minus 66%.
We in Columbus are used to that sort of "polling", and regard the Dispatch as the Democratic disinformation gazette.
When they find it necessary to announce their "poll", you can bet they are beginning to sweat.