It takes a dynamic person at the top to lead the rest of the flock to victory.

A Successful  Gubernatorial or Presidential Candidate that has coat tails in his or her election run can take seats that are running neck and neck and make all the difference in their parties quest to win on the legislative side of the political ledger. Look at Ronald Reagan in 1980 and Barrack Obama in 2008. Their successes translated to major gains for their parties at the polls. This is not always a given. Bill Clinton, George W, Bush, and Donald Trump had no coat tails in their first elections as President. Of course the later two were electoral college victors, not chosen by the people. That said, a strong appealing candidate is preferable to a dull unappealing one (even if the dull one is smarter; ask Jimmy Carter in 1980) and Progressives and Democrats should be seeking dynamic individuals that can catch the people's imagination for the coming Gubernatorial elections in 2017 and 2018.

http://www.governing.com/topics/politics/gov-state-down-ballot-races.html