Let's not be delusional. He is not and was never a 'world class striker'. The best stint of his career was being the third best striker for a team that finished mid-table every year and got kicked out routinely in the early rounds of a tournament where they played other slightly above mid-table teams from across the continent.
I hate it when people use the term 'world class' as a catch all phrase for anyone who's played in the PL or for a reasonably sized club on the mainland. 'World class' implies they are at the top of their class in whatever position. For instance, Lewandowski and Suarez (and messi and Ronaldo if you want to classify etheme as forewards) are forwards who are genuinely miles better then their competition. Therefore, world class. Defoe? not so much.