Responding to an eMail of mine on a Wagner list wherein, with the exception of Das Rheingold, I declared the Karajan recording of Wagner's Ring a "perverse joke" because of Karajan's bizarre conceit that Wagner - even mature Wagner - should be made to sound as intimate and lyrical as Verdi, a TOF (True Opera Fan; like a teenage movie fan, only worse - much worse) lodged objection, and went on to cite his reasons, all of which had to do with the singers involved.
How did I know the responder was a TOF? He went on, and on, and interminably on about the singers and the singing, that's how. The principal (but not sole) distinguishing hallmark of the TOF is that he's convinced opera means Italian-form opera, and is therefore about one thing and one thing only: the singers and the singing. Whenever one encounters a critique of a performance of a mature Wagner work (i.e., those works post-Lohengrin) that dwells interminably on the singers and the singing, one can be certain one is dealing with a TOF, and safely dismiss the critique as being near-worthless. TOFs imagine that the works of the mature Wagner are nothing more than Italian opera writ large and sung in German; a bit like saying the noble elephant is merely a piddling rock hyrax, only bigger and with a trunk.
The mature Wagner operas (more correctly called music-dramas) are, of course, nothing of the sort. They're animals of a different order altogether from Italian and Italian-form opera, and share with them only the technical apparatus of performance: an orchestra and conductor, singers, a sung text (libretto), an orchestral score, and mise en scène. Beyond that they've nothing in common.
If one were pressed to choose the principal element of a Wagner performance - that element on which the success or failure of the realization of the work most depends - the choice, hands down, would have to be the orchestra. Without a first-rate orchestra with a first-rate Wagner conductor on the podium, not merely a first-rate conductor, nothing - and I do mean nothing - can save the performance from being second-rate at best; not even were all the sopranos Nilssons, all the tenors Melchiors, and all the bass-baritones, Papes. By contrast, a performance of an Italian opera with a merely competent orchestra with even a mere accurate time-beater on the podium would prove just dandy if less than ideal so long as all the voices were superb.