I hate to break the news, but that's not the case under those studies.
Pew doesn't take measurements every year, nor from every country, but countries like Canada, Japan, the UK, Australia, India, Spain, Italy, Tanzania, and Peru still have a higher opinion of the US under Obama than they did under GWB. That's just a start. My guess from going through the map is more than half the countries measured by Pew still show an increase in opinion of the US over GWB.
Apparently Kool-Aid is available worldwide.
Perhaps it depends on the Pew chart you go to. You picked the favorable and the author picked the unfavorable.
http://www.pewglobal.org/database/indicator/1/country/81/response/Unfavorable/