at dw.com I read an article from author Michael Knigge about Trump and Bannon. Currently, I try to improve my english tenses related grammar skills. Therefore I want to ask, what do you think Michael Knigge wants to emphasize on this sentence:
"But since speculation of Bannon's impending ouster had been circulating for weeks already and gained traction since John Kelly became White House chief of staff, the interview may have been the straw that broke the camel's back."
Moreover, when I try to figure out, if the tenses are used correctly - those are my thoughts:
* 'since' will lead to perfect - had been circulating (Action A), the related event in the past 'John Kelley became ...) (Event related to Action A) needs to be put in simple past. Question: so here is an exception to the rule 'since' (the second one in this sentence) needs perfect?! Emphasize on the duration of this period - therefore the usage of had been circulating.
* 'may have been' - simple present perfect, because the action began in the past and the consequences to the present should be emphasized. It makes no sense to think about the progressive form is more appropriate, because it is just an event and not an action with some kind of progression.
Thanks in advance for your thoughts on this sentence or a feedback, if my toughts are correct.