Your negativity towards Bell may be over the top, but your point has been proved over the last year or so and throughout his career. Even though England have lost world number 1, it's an important innings for Bell tomorrow; a big contribution would help reverse the idea that he's one who cashes in nicely against moderate to weak attacks, and then performs averagely to poorly against stronger ones.
As you said when attacks like Sri Lanka and India came, he had no problem in scoring big runs at a fast pace against these poor attacks which had already been flattened by Cook, Strauss and Pietersen. Then he went to the UAE where the attack was much stronger, and you confidently predicted him to be a complete failure more so than anyone else on this board, and you were correct. Some gave Bell the benefit of the doubt after this, and dismissed it down to conditions more than the strength of the attack, and expected him to be back and performing in English conditions.
Against West Indies he looked back to his best, but even then typically his top score came in a dead match, and West Indies are nothing more than an average attack. Now with a proper SA attack, Bell has found it very tough. To his credit he has fought hard and managed to scrape together a few 50s, but he has looked a shadow of the player that dominated last year. He's a good player but nowhere near as good as was made out during his golden period. Tomorrow he could start proving me wrong.