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I am not a guru - and there are plenty adwords experts here, maybe they'll drop by.
Think of it like a portfolio of stocks - some do well, some do badly. The bad ones decrease the performance of the portfolio overall. If you could shift your money from bad stocks to good stocks you would raise the performance of your portfolio overall.
And there are 3-5(?) different Quality Scores as well.
So I'd remove/ pause your under performing keywords.
I would move all my under performing keywords to a separate ad group and replicate the ads, this will help your current ad group in that it will lift up your CTR since the current group only has well performing keywords with high QS.
As for the underperforming ones, you can now separately work on them within the new ad group to tweak them individually and get their performance up over time.
That's the approach I would normally take...
hope it helps.
As far as placing them into another campaign, deleting or pausing them, I'm not so sure that's the right course of action.
How have your CPC's changed?
If, as long as the poorly performing keywords still have a good QS, would it hurt the overall performance of the ad?
Why aren't they performing, if the QS is 10 and they are at position 1 then this would suggest that people just don't like to click on that keyword and Google knows it (hence the QS) If it's that the bid isn't high enough, it would depend on your reason for not increasing the bid to increase the click through.
Essentially though, if the QS on the keyword is good, this would suggest to me that the keyword is performing as expected for the position and bid price it has and there is no reason to think that it will have a negative impact on the campaign.