First of all not Russia, but in Russia. This is about the traditions of deploying defencemen in russian hockey in general.
I will preface this by quoting myself from the Alexandr Alexeyev thread.
There are several factors. From playing on the larger rink derives the tradition of playing 4 defencemen pairings and distributing icetime between them more evenly. It is basicallly fresh legs over skill. Given the level of this year's D squad this is a good strategy. There is no standout 1D or top pairing. Then the so common in NA lines and pairings are not at all common in Russia. If a russian sports site publishes russian rosters it never goes like this
It goes like this
Ларионов о первой тренировке молодежки: «Довольны, что все вышли с карантина. Брака после простоя было не так много»
It is always 5-man-units.
That is not just a tradition. You obviously can't play with 5-man-units with the usual NA roster with only 6 D-men on it. And not only it is in general the intent of russian coaches to create cohesion withn those units, but Lerionov explicitly stated that is trying to recreate some of the soviet traits on his team he was used to as a player. He also stated that he wants to spread the scoring as much as possible(while for now the lineup still has a clear cut top forward line with Amirov-Khusnutdinov-Podkolzin). He has three offensive minded defencemen in Knyazev, Chayka and Mukhamadullin. Two of them are 18 though. Larionov obviously looks to distribute them to different pairings AND also looks for chemistry between his D pairings and forward lines. So when Knyazev is "on the third pairing" in the eyes of the NA writers, he is actually on the unit with a 18 year old(as obviously Larionov does not want to put the younger kids on a pairing together) D man and one of the better snipers on the team in Afanasiev who has 6 goals in 9 games this season in KHL, MHL and on the NT. This has also absolutely no bearing on how many minutes Knyazev will get(as explained in my quote above) or his deployment on the PP.
And yes, I wondered why the otherwise hysterical canadian writers were sleeping on Chinakhov being "on the 4th line". Voila, they did not disappoint. Here they are not not doing any research again and not understanding that what they see is not the typical Team Canada roster.