If you saw your average position drop week over week, what would you do?
I am sure you are asking about Google Search , “Possible reasons why Avg Position of Search Ad falls?”
Avg Position or Ad Rank is a factor of Avg CPC & Quality Score of Keyword
Breaking down the above : Avg CPC - This is purly how much Max CPC bid you enter for your keywords. If you reduce your Max CPC bids, this means that you are willing to pay less for each click. Hence google algorithm thinks that, you would want to enter into auction with a lower Max CPC bid. If your Quality Score was same, then lower Avg CPC can be linked to drop in position week on week.
Also, lets consider a scenario,where you have not changed the Max CPC bids, then in this case, go to Auction insights Tab. If you see that other advertisers have become aggressive week on week, (they have started bidding on same keywords as yours), then even in that case, Google Algorithm will recognise that your Max CPC bids are not competitive enough and hence will result in lower positions.
Lets assume another scerio: Quality Score. Now Quality Score is a factor of Ad Relevance, Historic CTR and Landing Page Experience, and Ad Depth (Ad extensions). Reason for fall in avg position may be due to Fall in Quality Score, which may be due to any 1 or more of the above 4 factors. If you change the ad copy, the ad goes in to learning and it may result in change in Quality Score. Likewise if you change the landing page, then Quality Score may change and may also result in fall in Avg Position.
Hope this helps.