Yes. Being that Janet Yellen was a stout supporter of many policies that came to fruition under Bill Clinton, and are now viewed as negatively effecting the long term economy, I would say that she would most likely harm the economy more than she would help it. Mainstream economists have been so sheltered from the actual situation in America, that it will be very difficult to nominate someone that can actually restore the economy.
No one getting appointed to the office of the Federal Reserve does so with a track record of being incompetent. Aside from the President, it's likely one of the highest offices of trust in our government, charged with the well-being of our economy. Janet Yellen is the right choice for this position, and should be confirmed.