The Tiobe ranking looks just plain wrong. It would be interesting to know how exactly they're calculating and interpreting search engine traffic.
Their method means that, in general, their numbers will trail changes in programming language popularity. For example, if everybody stopped using JavaScript tomorrow, there still would be millions of hits on +”JavaScript programming” for years to come.
Also, their methodology overrates languages many people wrote about or those that trigger more questions online. I would guess it underrates COBOL, for example.