On the one hand, you and Rove are absolutely correct that the most important factor — by FAR more than half the pie-chart — is the POTUS nominee, not the VP.
But I think you overstate it when you say the VP doesn’t matter at all, or, at least, can NEVER matter. Yes, there are plenty of VP-pickings that were made in hopes of this or that benefit, which didn’t pay off. That doesn’t show that the VP can’t help a little around the edges in some elections.
I think Cheney was a huge asset for Bush.