Wrong again, Iago.
That has nothing to do with practices like this. The Orchester der Wiener Staatsoper and therefore the Wiener Philharmoniker have enough full time musicians to man (and since recently, even wo-man in a few cases) two orchestras, and so does the Kirov Orchestra. The WP have around 150 members or so, and then they can also invite extras, of course, the Kirov has a huge orchestra, probably around 190 or 200. That can easily be seen by clicking on the link 3 posts above, then "orchestra", then "musicians". I haven't counted them, but based on how large the wind sections are, they might even have over 200. In fact, I don't think I have ever seen an orchestra with such a huge roster. Even the Gewandhaus which does full time opera and concert and which has 192 members appears to have "less" members.
Well, what M says sounds like perfect sense. I did not hear them in their Covent Garden appearances, but I do recall the surprise I had on reading the Sunday papers in which they got a real drubbing for their Verdi, not just the playing but the productions and the supposed clear under rehearsal. The Russian opera, (I think it was Boris), within the run got good reviews.
It has been mentioned before that Gergiev can sale close to the wind and from what the newspapers reported, the non-Russian operas were poorly performed all round. As I was not there I am only passing on what stuck in my head, as I had assumed they would get the glowing reports they had previously garnered.
As far as the Wagner in Wales is concerned, it was given terrific reviews for the orchestral playing and Gergiev's conducting. The production was pretty much detested.
I wasn't there either, but we are talking about the quality of the orchestra in general, and that is very good, without any doubt, nothing that deserves to be called "not even third rate" by a complete amateur and ignorant. Respect for the artists is the basis for any real criticism, however strict.
It is true, Gergiev's sometimes...uh...improvisational style brings an element of unpredictability in here, and that can certainly lead to less than ideal individual performances now and then, but as we all have had opportunities to hear, maybe even live or at least in live recordings, this ensemble can deliver truly outstanding results. The "spontaneous" approach certainly holds some dangers, but then it can also result in truly exciting "live" events which carefully planned and controlled "safe" performances rarely do.
After all, it is a "live" art form.
I agree about the Wagner, what I have heard from that was very impressive orchestrally. It had a slight, but not very strong "Russian" sound and feel to it which may not be entirely "authentic". But it was still musically and orchestrally very, very good and maybe all the more interesting for this "exotic" element. And you know what? They still sound more like a "Wagner orchestra" than the MET ever did. The MET orchestra is technically very good, but they don't sound much like anything. They certainly lack the depth of tone and the sheer weight of sound this music sometimes needs, and the Kirov has that, even if it is a slightly "Russian" sounding kind of weight.
Which brings us to those reviews. Neither you nor me were there, but reading between the lines, the Russian operas "great", the Italian operas "terrible", that simply can't be even if one evening can indeed be good and the next disappointing. But that sounds much more like disappointed cliché expectations, maybe about how "Russian opera has to sound" - pass, after all this is a Russian ensemble, it must be "authentic" and about how "Italian opera has to sound" - fail, after all what is "authentically Russian" somehow can't be right for Italian music. Which is bullshit of course. These Russian musicians may not be from as sunny a place as their Italian colleagues, but they are still very good musicians and they still know much more about Italian music than some newspaper critic, even though he may go to the Toscana for his summer holidays once in a while.