Are there any official press releases from the Bolshoi that announced Vaziev as head of the Bolshoi? ....
None whatsoever. I believe that Angelique was using the words 'press releases' in a more general sense, to cover a statement in the press (an article in a newspaper) rather than formal press releases from the Bolshoi, so I continued her train of thought on 'press releases' but, no, there were none. The only formal press release appeared when Filin was named.
To be clear for our members for whom English is not their first language, the single definition of a press release is a stand-alone statement released by or by a surrogate of a company or person, usually to the press, who may print and edit it. It is not a sound bite or part of an interview with company officials or members on a topic.
There may be an unauthorized press release, where someone jumps the gun and releases a spoken or written statement that was not agreed on by the company or person. There may be rogue statements that are made to appear like official press releases, where the medial is fooled. There is no such thing as an "unofficial" press release.
The distinction is important, because Dancer A or Associate Direct B or Arts Official C may have given an interview and/or have been quoted as saying "We wanted to hire Maziev to run the Bolshoi". This is not a press release. This is a statement to the press.
The rules on Ballet Alert! are similar in both cases: there must be a citation substantiating the assertion. For example a statement like "the position of Artistic Director of the Bolshoi had been offered to Makher Vaziev first and foremost, fact which is supported by numerous press releases of the day [or was widely reported]." must be substantiated by citations to actual press release(s) or press statements. It is fine to say that the official press release/press statement was published in "Newspaper A", "Magazine B", and discussed on TV Station C, and was picked up by numerous other media outlets. "Numerous" alone is unsubstantiated.