No, he doesn't get all the blame. But he was sure quick to assert his prerogatives when intervening in the party's nominating process this year. Here's the Republican share of the aggregate vote for State House of Representatives since 1996:
Notice a pattern? There's a slight rise in 2000, probably because of the Presidential election, but this is a governor without coattails. The 2004 win by the Dems was exaggerated by the Four Horsemen, but this was seizing an opportunity as much as anything else. I'll repeat: Owens at the state level has been to the Republicans what the Clintons are to Democrats nationally: very good for himself, very bad for the party.