Hahaha. I've talked about this before.
No matter how well the Republicans do in the near future in Massachusetts, Romney will never win the state again. Remember, it was because of Romney that the Republicans were kicked out of the governorship in 2006 to begin with. Romney is, if anything, the last Republican I could see winning the state. When he left office in 2007, 65% of Bay Staters disapproved of him, and only 30% approved.
For what it's worth, Romney was absent from the campaign trail. If Romney were present, I think Brown would have had a far harder race.
You seem to forget that were it not for Romney, the GOP would have lost the Governorship in 2002.