Stoychev's Trentino and Alekno's Zenit, both offensively powerful and relatively fragile in reception, surely have tangent points, I completely agree, yet I cannot concur with all points you made. Sure, the Zenit vs. Perugia final reminded of the Trentino vs. Dinamo Moscow back then. If you look at only those two matches or just the stats of those, you would find (only) many similarities indeed. Let me start with the differences then, in my opinion.
First, Zenit HAS to recruit (all) the best Russian players due to the league's foreigners limitation. This directly leads to a significant reduction of the level of local competitiveness. OK, Russia is huge, they still have maybe enough talented players scattered in clubs across the country, but we have seen that in theory Zenit (and maybe Gazprom money) plays a part in making the league boring. Which, we have to agree, wasn't the fact in Italy back in Trentino's golden days. In fact, the league wasn't boring at all, for there were Trentino's black cat Sisley Treviso, Giuliani's Cuneo and even Modena and Macerata - all teams that could win against Stoychev's side. If this is something that we can agree on, then surely Trentino's European reign didn't bring along a guaranteed domestic one. You are absolutely right that no one likes to watch the same winner over and over again but, albeit seemingly boring at times, those team's campaigns stand out and we can be considered fortunate to have witnessed them, as it means these involved super teams indeed. Besides, remember that such runs of successive titles have always existed and were even more disheartening for opponents on national teams level, for instance. I don't really consider them a real plague for volleyball and I surely don't consider Trentino's peak a plague for Italian volleyball in general, as I pointed out above. I am not that sure about Zenit, though...
This is not entirely correct. Zenit does overrecruit local players and there are always talks about them accumulating the talents brought up elsewhere. But I have to say, this occurs episodically. They indeed headhunted plenty of top experienced players in the past (Ball, Tetyukihn etc), which let them win their first CL. Mikhaylov was also one of the big fishes. Then had two NT members on the bench last year, and last year they grabbed Butko and Volvich. But if one looks at their roster for 2016/17 season, there isn't much of depth in there, beyond the starting six. Gutsalyuk, Melnik and Zemchonok are very average players. Take a look at their closest competitors from Moscow - now these guys had a decent roster indeed, and it is them who actually deprived the competition of a decent team, just because they had two equal squads. Antipkin, Biryukov, Ilinykh, Bakun, Volkov - these chaps all played for the NT in the near past. Furthermore, if one checks what Belgorod has in its depth, then surprisingly there would be also an OK squad made of local-ish players. Had Rus league been played without the foreign players this season, Zenit would have struggled for a medal, not more than that.
The real "problem" is not the financial dominance of Kazan - it is about financial troubles in Belgorod and Novosibirsk and a clear lack of planning in Moscow. Well, the latter partially applies to Belgorod too: note how badly they were trashed by (a nominally weaker) Novosibirsk side in the bronze match, just because Lokomotiv had a reasonable coach and a reasonable idea of what they want to achieve. You see, the trouble is we're discussing the dominance of Zenit, whilst the opposition to Zenit is frequently doing things unrelated to competitive volleyball, e.g. bringing in an incapable President's son-in-law for a couple of sets or employing absolutely random people in the coaching process. Alekno's son was indeed present among the rest in the champion's squad but for some reason noone let him lead the final/semifinal game. Planning-wise, Zenit is not ideal overall as there were blunders like e.g. Toniutti. But their direct competitors from Moscow and Belgorod are by far worse in this field. Do recall Ivan Zaytsevelli who's been pushing the ball-basket in Moscow for a couple of years whilst being paid very well. Take a look at Belgorod recruiting strategy. They need a replacement for ageing Khtey - Marco Ivovic is recruited. He's not bad at all but he's not a tall receiver/side-outer with a decent block. Belgorod has a setter crisis every season - there will be someone coming or going etc. After that, there is a bunch of weird factors like the unavailability of Panteleymonenko for Belgorod, who seemingly fell out with his bosses in Krasnodar and remained out of squad for a season.
Second, the squad recruitment the set distribution wasn't quite identical for both teams. Kaziyski and Leon are comparable, fully agree. Juantorena and Anderson, who often doesn't play an amazing role when Zenit is in trouble, are not. Butko and Zygadlo aren't comparable either (to Raphael, however, he surely is, from a sports perspective, not technically). Verbov and formerly Salparov bring way more stability in reception than Bari. Zenit's MBs are in general (slightly) less used than Trentino's, Raphael liked to used them a bit more. Vissotto and Mikhaylov may be comparable, but Mihkaylov to Stokr surely not. The list leads to the following point I want to make - Trentino appeared to have some weaker elements overall, but seemed to play with more diversity and still dominate. The other big difference was that you weren't always sure (it wasn't always only Kaziyski or Juantorena) who will get the important set when times got tough, whereas Butko would trust only Leon then.
This is all debatable. Mikhaylov in 2016/17 looks better that Stokr or Vissotto in their best seasons, Mikhaylov a year ago looked worse. Trento had more experienced MBs and Rafael was technically by far more gifted than Butko. Zygadlo is definitely better than the wooden Igor Kobzar. Regarding total dominance in the home league - do check when and by how much Trento won the regular seasons and compare this to the record of Zenit. In the end, as you have correctly admitted, Trento was in a position to sign essentially anyone which made them a real around-the-world team. Zenit has only two spots. Leon is once again the most spectacular player but do check who scored the important winning points this season. Btw, statistically, Mikhaylov is way ahead of Leon in 2016/17 too.
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Last, yeah, maybe Cruzeiro nowadays is better than Cruzeiro from 5-6 years ago, but they still had the main core of players. And Trentino got them nevertheless. I am not quite sure that the old Trentino wouldn't have been able to handle them nowadays, but it will remain a discussion topic
You can check the records, there were certainly years when the best South-American team didn't pass the semi-final mark. Trento faced them once in the final in Doha back in 2012 - but there's been very palpable changes since then for both teams.