How Does the Newspaper Review Help Us to Understand Callas's Reputation as a Diva?

Jay S. Harrison’s 1956 review of Tosca played by Maria Callas does little in helping us understand Callas’s reputation as a Diva, as it merely concentrates on her singing and acting without mentioning her career or her life off stage. In fact to the ordinary person the review may even seem somewhat confusing.
The initial impression left on the reader’s mind is that Callas was very ordinary in her singing and acting.
“On the basis of her present performance this much is sure: her soprano is not big, nor is it of a quality even approaching velvet.” (J.S. Harrison (1956) review of Tosca at the Metropolitan Opera House)
Harrison starts his review of Callas very negatively; he then clarifies himself and makes a distinction between the two acts of the play: the first being quite ordinary but the second electrifying. This is further explained by asserting that Callas possessed a “dual remarkable nature.” (J.S. Harrison ibid)
According to Harrison, in the first act, Callas was disappointing, very ordinary, not worthy of her reputation that preceded her.
“Her portrayal was rather pale, her entire manner was not with her, and she seemed distant, remote, her voice as well, taking on those qualities. In consequence, the electricity native to the act was no brighter than that produced by a five and dime flashlight. (J.S. Harrison, ibid)
In the second act, Callas, according to Harrison was magnificent. She was “transformed as if by witchcraft”, (J.S. Harrison ibid) she lives up to her ‘Diva’ expectations; her performance is electrifying and flawless.
“Her voice steadied, it’s pitch punctured notes like so many tooled arrows, and it’s color lightened, brightened and finally glowed.” (J.S. Harrison, ibid)
“She reacted to the hideous net of events gathering around her exactly.” (J.S. Harrison, ibid) “Her despair at Cavaradossi’s torture, her revulsion over Scarpia’s lust, her resignation as she realizes that she is she is lost were all tightly etched in her face; and...