Considering the political climate in 2010, I'd say the reverse. Her endorsement cost the Republicans 21 seats.
Even if that were true (which it isn't), it still makes her relevant.
2012
http://abcnews.go.com/Politics/OTUS/palins-endorsements-work-underdog-candidates/story?id=16368551
Palin's Endorsements Still Work With Underdog Candidates
If you're an upstart Republican running for your life in a primary in the middle of the country and hoping beyond hope to gain traction against the "establishment" candidate, who you gonna call?
Sarah Palin could be the answer.
In 2010, Sarah Palin was the sought-after kingmaker for establishment and upstart candidates alike hoping to get her blessing to help them make it to Washington, D.C.
She had a strong record of endorsements to wins then, but after remaining out of the spotlight after deciding against a presidential run, does she have the same influence two years later? With two wins under her belt so far and a stake in Texas ahead of a primary there next month, could Palin and her ability to help out the underdog be back?
ABC News' political analyst and longtime GOP analyst Matthew Dowd described Palin as the "spark" that can light the fire of certain campaigns.
"Singularly, she doesn't win these races," Dowd said. "But if there is a forest with a bunch of kindling, she puts a match and a light on it. The forest wood had to be dry, but she's a spark."
He also points out her record, which has some high profile wins, such as state rep. Deb Fischer in Nebraska for that state's U.S. senate primary last week. Even some of Palin's losses have been victories of a sort. She backed Christine O'Donnell in the 2010 Delaware U.S. senate race and Sharron Angle for the U.S. senate race in Nevada in 2010. Neither woman won the seat, but they both upended establishment favorites in the primary.
"If I were a long shot taking on an establishment candidate, Sarah Palin is who I would want to come and charge up the race. She would be number one or two on the list," Dowd said. "She has as much ability to charge up the race as a former president."
And while her record is not perfect, she has backed two successful upstarts.
The former Alaska governor backed Richard Mourdock over Dick Lugar in the Indiana U.S. senate primary. But so did many Tea Partiers and other conservatives. He beat the six-term senator by 20 points.
It was more impressive last week when Palin made a late-in-the-game endorsement of rancher and state rep. Deb Fischer. Fischer sailed to victory Tuesday night, defeating both Jon Bruning, considered to be the state party favorite, and Don Stenberg, who had the backing of Tea Party groups.
(more at the link)