Unfortunately, she was not enough to overcome everything that was wrong with the McCain campaign, which again goes back to my point: that the candidates and their campaigns have a lot to do with their own success (timing and their hard work are more important than any endorsement could ever be).
If anyone has any data that shows otherwise, I'm happy to look at it, but since you specifically mentioned the TX Senate primary, she did not boost Cruz to a win, as we can see from the polling which showed Cruz in a position to make a run-off, then win (both prior to her endorsement and later arrival).
To suggest that an endorser is a kingmaker because of their endorsement does a disservice to the hard work of the actual candidate, their campaign & volunteers, imho.
Funny that almost all of the candidates from 2010 and this year disagree with you and credit Governor Sarah Palin with significantly boosting their campaigns, if not being the decisive factor. Google it.